It’s an interesting question. I don’t play poker, but have no problem with others doing so. But you single out the key point: it is a game that people wager on. They are wagering on themselves, but it’s still an unknown outcome with luck being a significant (if not singular) variable.
Is it against the law (as opposed to against the rules) for a professional athlete to bet on himself to win? I don’t know, but if it is, I think the same standard may apply to poker players. You could carve out poker by law, of course, but I don’t think you could say Phil Helmuth can gamble on himself in a game legally but Derek Jeter cannot.
Also, aren’t there negotiated pot settlements in poker, which would be kind of like tanking?
Can a golfer bet on himself can a tennis player bet on himself, we’re not talking teams where ones performance can hurt or influence the whole team.
Sir if I had to rely on luck to play the game of poker I would not play.
I don’t think it is illegal for athletes to bet on themselves, it’s just banned by the leagues and athletic associations. If it were illegal for athletes to bet on themselves, then we’d have to ban any tournament that charges an entry fee and awards a cash prize. That’s no different than wagering on yourself winning the tournament.