I think you pose a great question and I look forward to reading the responses you get. I haven't played poker long enough to know the answer myself.
My suspicion is this: even though a good player can beat a grandmaster in a single tournament, given 1000 tournaments, the good player will never be able to beat the grandmaster most of the time. Never. If that's not the case, then poker doesn't allow for the mastery edge you describe.
But what percentage can the good player expect to win? 200 games? 400? I really have no idea. I'd love to hear what others think on that one.
Poker is difficult to compare with chess since a good chess player can never beat a grandmaster in a single tournament. It just can't happen. That's because in chess, there is no luck. In poker, however, we all know that a 90% favorite still loses 10% of the time. And variance can pump that loss percentage even higher in the short term.
That's what I find fascinating about tournament play. Even if I'm an 80% favorite at every all-in showdown, I can only go there so many times before I'm out of the tournament. The survival factor is more complex than just playing the odds
every single time.