I doubt that they would make exit scam just for $20k or similar amount of money. It's just not worth.I have no idea how much money they invested to make website, all promotions and how much money they were making, but I believe it' way bigger money.
Betnomi had a small number of active gamblers, even it was decreasing gradually for their poor services. I believe their casino and sportsbook weren't able to generate as much profit as they were spending to run the casino. Eventually, they found it better to close the casino with the funds of the user. Based on the reports of 4-5 users in Bitcointalk forum, they had almost $50k on their Betnomi account in total.
BTW, Casino Guru has marked Betnomi as a '
closed casino'.