Instead of spending Passover with his family, Asher Conniff spent time playing poker. A professional player, Conniff was cornered into taking part in the World Poker Tour (WPT) Tournament of Champions, an invite-only event for former WPT winners. As the 2015 WPT World Champion, Conniff couldn't turn down free entry into the $15,000 buy-in tournament. He said it was "a major Jewish holiday and I would like to be home with my family". "But," he reflected, "I play poker for a living and they chose to schedule it when they did."

Conniff wasn't the only Jewish poker pro disappointed by the scheduling. Players took to Twitter to complain. Poker writer Robbie Strazynski, an Israel-based Orthodox Jew, told me: "I believe a lot of Jewish poker champions who qualify for the event will be skipping it." Strazynski turned down a trip to cover the tournament - "it's more important to remain involved in the tradition."

The idea of making a living playing poker might seem far-fetched, but a hard core of American professionals travel the poker circuit, making millions.

As a live reporter at the World Series of Poker (WSOP) in Vegas, I was approached by Belgian poker pro Baruch Thaler, who asked if I'd thought of writing about the poker scene's Jewish players. Orthodox himself, Thaler told me he couldn't play in The Main Event, WSOP's most prestigious tournament, as it spreads over seven days, including the Sabbath.

There were other tournaments Thaler missed because they fell on Jewish holidays, and keeping kosher during long days in tournament rooms meant pretty much living on muffins.

I spoke to more Jewish players, including Canadian born Ari Engel, a recent winner of the Aussie Millions, who has amassed over $3.5 million in winnings. Engel lives out of a suitcase, travelling to tournament stops - we began our interview in Barcelona, and continued it in Prague.

Engel's childhood was spent moving around - both his father and grandfather were rabbis. Often seen in a kippah, Engel told me: "Poker players underestimate religious people. When I wear it, people tend to think I'm inexperienced, so there are advantages!"

American poker legend Barry Greenstein is a Team PokerStars pro who has racked up a WPT Championship, three WSOP wins and more than $8 million in winnings. He has been playing poker since the 1970s and recalls: "In the old days, we talked about two groups, Jews and Texans - we'd bet on which group would do better. Jews came from a big gambling culture, and Texans came from Texas, which is where the game came from. As poker got bigger in the early '90s, there became three groups instead of two - we called the third group 'foreigners'!"

Greenstein grew up playing cards with his mother, who gambled in the synagogue. At the age of 10, he watched her play gin rummy with his six-year-old brother and noticed she was letting him win: "I said: 'Mom, what are you doing?' She put her finger up to her lips, and she whispered to me, 'you think I didn't do that for you, too?' I had a pretty great mother!"

American pro Ronnie Bardah, son of Israeli parents, is a WSOP winner with over a million dollars in winnings. He learnt to play poker from his dad: "My father was playing cards his whole life, so I grew up around it. Whatever the casinos made their money off, my father was there donating." At 19, Bardah started playing poker, losing the money he earned in McDonalds to his dad. By 21, he was making more than $50,000 a year playing cash games. He says: "It wasn't a decision for me - I didn't have anything else.

"I was punching the clock and wearing a name badge. I played cards for the freedom."

Bardah says his dad was happy for him to play poker for a living: "My parents don't have any money whatsoever. I'm the most successful one in my family. My dad would say: 'I wish I didn't have to go to work, I wish I could play poker like you.'"

Greenstein's mother was similarly supportive. "She thought I'd grow up to be the president of the United States but, when I told her I was a poker player, she said: 'I'm sure you'll be the best!'"

But not everyone had unswerving support. Matthew Wantman is a relative newcomer to the poker scene - and has made almost $300,000 this year. He says: "My mother was very anti-gambling. She used an IP address blocker to firewall poker sites. She wanted me to go to university - I ended up going for a semester." Wantman says his mother became more supportive when she saw the money coming in: "She's results-oriented."

Conniff's mother also took convincing: "Jewish mothers can't help but worry about everything in the world and this was no exception. One thing I'll always give her credit for, she didn't push me to become a doctor - she just wanted me to be successful and happy."

Melanie Weisner's wins include EPT events in Monte Carlo and Prague, and a WPT in Johannesburg. She says: "As long as I've been successful supporting myself, it's never been an issue. My parents' attitude is acceptance, with a little bit of disdain."

I asked Strazynski what percentage of successful pro-players are Jewish. He said: "It seems like everybody, right?" Bardah also commented that there are lots of very successful Jewish players. I asked him why: "Jewish people are pretty smart. We're business oriented, we're critical thinkers. Most Jews are pretty successful, whatever they put their minds to." Wantman said: "We value our money, so when it comes to gambling, you try to minimise the risk and maximise your edge, and treat it like a business."

Conniff offered a different perspective: "Playing poker requires a set of skills anyone can have. I don't think one set of people is more apt to be good at poker than another. But poker is hard to play professionally if you don't have, or come from, money. If you need to pay your family's bills, it's hard to take that money and play poker. The median Jewish family income is higher than most others."

In Greenstein's view, "Jews are good at maths and we've had Jewish psychologists since the early days of psychology… Those are the skills you need. When people ask me what to take in college to be a poker player, I say a major in psychology, a minor in maths."

Tournament days are long. Unless you're eliminated, you can easily spend 12 hours at the poker table. I asked Thaler how he managed to eat kosher: "I eat cereal in my hotel room on my dinner break.

''If I'm in Vegas, I go to a kosher restaurant called Jerusalem Steak House. Otherwise, I eat muffins, Pringles or salad. Once in a while I eat kosher chocolate like KitKat."

Engel told me: "When I first got into poker, I was super strict. I'd travel with all my food - I'd bring dry stuff and add hot water. Most hotels you can find a bagel for breakfast, then I'd have fruit and granola bars. Even today, I consider access to kosher food when I'm picking tournament stops - it's definitely a plus."

Other Jewish players have an easier time. Weisner says: "I'm mindful if I'm with people who are kosher, but I'm pretty lax in terms of observance. It's not a factor when it comes to tournaments. I've posted countless pictures of me eating bacon."

Tournaments tend to take place over several days, often over the weekend. Thaler, who has won two WSOP Circuit events, told me he had petitioned the WSOP: "About six years ago, I got signatures from 20 pro players, asking the WSOP to rearrange The Main Event, not to be on Sabbath. I gave it to [Tournament Director] Jack Effel. He said the only time he rescheduled a tournament was for Yom Kippur. I told him that, to me, the Sabbath is equally as important as Yom Kippur."

I asked other Jewish players how they felt about tournaments taking place over the weekend. Bardah said: "I play, but if I met a nice Jewish girl, who wanted me to make a good example for the children, I would try not to play on Shabbat. If it was a big tournament in the World Series of Poker, though, I would have to!" Engel, who grew up Orthodox, says: "Until I was 25, I was pretty strict. Saturdays didn't just mean no poker, they meant no driving or cooking. I sat out of The Main Event for a few years, rather than play on a Saturday.

Neither Engel nor Thaler play poker on holidays such Yom Kippur and Rosh Hashanah. According to Thaler: "I lose a lot, but I'm hoping to be rewarded for that - and there's enough money to be made outside the holidays."

Engel says: "You've got to take off days anyway, so you just take off those days. I'm fine with it. I usually go and visit the family. There's so many tournaments, it's not a huge issue."

Barry Greenstein told me that, as a well known Jewish player during the poker boom of 2003 to 2006, "Jewish kids in yamulkes would ask me to advocate for them. They wanted to play poker, but tournaments were falling on Passover or across the Sabbath. I told them to come into the 21st century."

Greenstein explained: "It's great to celebrate your culture, and if you're Jewish, you can't deny the role religion played in keeping people together - but religious people trying to assert themselves in modern times is one of our biggest problems."

Weisner plays on Shabbat and describes herself as, "on the more reformed end of the observance spectrum" but she doesn't play poker on Yom Kippur or Rosh Hashanah.

At a tournament stop in Cannes, over Yom Kippur, Weisner located a synagogue: "Cannes is not a notoriously Jewish city and nobody really spoke English, but when they discovered I was American, they found me a prayer book in English."

The tendency to schedule tournaments on Jewish holidays doesn't go unnoticed. Nancy Birnbaum, one of only two female players to win three WSOP Circuit events says: "I've accepted that they're not going to run a tournament on Christmas, but they'll run one on the Jewish holidays."

Strazynski echoes this: "It's a no-brainer that no poker tournament would ever be scheduled on New Year's, Christmas, or Easter." Wantman adds: "A couple of weeks ago, I was playing in a tournament and they skipped a day for Easter. There aren't enough Jews - we don't have a big enough voice."

Strazynski says: "I don't think it's a case of, 'let's see how we can screw the Jews!' But organisers should take care to schedule tournaments on the clearest calendar day possible." Engel points out: "I don't think Orthodox Jews are poker's target market."

Out of the 227 players who were eligible to enter the Tournament of Champions, only 64 signed up, and it was won by the relatively unknown Moroccan player, Farid Yachou.

For Conniff, who crashed out of the tournament on day two, leaving with nothing, it was just another Jewish holiday he'd missed spending with his family:

"I've been on the road with poker for a few years now, so I'm a little out of touch. It's been a while since I've been a true Jew."