I did a Google search and found this high in the search results:
https://www.journalofaccountancy.com...-gamblers.html
I think these are the key words for kewlj and redietz and mickeycrimm:
" In Groetzinger, 480 U.S. 23 (1987), the Supreme Court established the professional gambler standard: "If one's gambling activity is pursued full time, in good faith, and with regularity, to the production of income for a livelihood, and is not a mere hobby, it is a trade or business." The burden is on the gambler to prove this status."
What is full time? What is full time for a Vegas player who commutes from Arizona?
What about a professional poker player who only plays in a dozen big money tournaments in a year? Is he not entitled to file a Schedule C because he doesn't sit at tables 40 hours a week?