Not taking +EV bets that represent negligible portions of your net-worth is epistemically irrational so it seems like a rationalist community should be encouraging betting when it is done at reasonable stakes as a way to train or test beliefs.

After some amount of practice, playing poker should be +EV. Betting money while still a poker noob, however, is certainly -EV. I'd be more willing to bet money if I had some indication, preferrably in the form of an Elo rating, that I can expect to come out ahead.