I believe over multiple poker hands that advantage from luck would quickly diminish and then disappear. I would be very surprised if any normal chess player, a total novice at poker, would be able to beat the best poker player in the world if they sat down to play for a couple of hours straight.

Skill would win out, but "hours" is not even the right ballpark.

For comparison, 50K hands is a standard length for heads up matches between pros, with the understanding that even then the best player is not guaranteed to win. In live play, you'd be looking at 50-100 hands per hour.

It's true that with a greater skill gap you'd need less time, but you'd still be looking at thousands of hands if you wanted something like 95% confidence that the better player was up.

Variance in poker evens out over months, not a single session. A competent but not great player can definitely beat a pro in a single session.

I think you're overstating the variance. If you watch high level poker play you will consistently see the same players at the final table of big tournaments. Sure, a few lucky random players will go pretty deep in the tournament, but they just don't do it nearly as frequently as the top few guys.

A competent but not great player has a chance of beating a pro in one session, but it's definitely pretty slim.

When poker players measure variance, it's $$$ over time. And while some pros are indeed good are surviving the bubble in fishy tournaments, none make a perfectly consistent income. Even amongst crushers, the variance can be massive.

For every tournament you make a big score, you crash out of 5 and get min payout on a few more.

Many of the biggest names in poker have been the biggest losers in a given calendar period. For example, Gus Hansen and Daniel Negreanu are two of the biggest winners of all time yet also have some of the biggest documented losses...

Not clear how long your "sessions" are but they have poker tournaments where the same people regularly make it to the top.

Not as regularly as you think. Earnings vary a lot.

As for how long a session is? 8 hours. I made a living from poker for a few years.