I would include a fair player who is sponsored/represents a pool company and can support himself with his earnings. prize money plus salary for doing trade shows/exhibitions/etc.
What does he put on his 1040??
No idea if this is still true but years ago if you weren't making a net yearly profit at something after five years, maybe seven, it was a hobby according to the IRS. That would turn a lot of pro pool players into hobbyists I suspect!
The IRS would make an exception but only if you could show it typically took longer to get in the black. Maybe an orchard would qualify.
Hu