Glory
If you win a million dollars, who cares who's watching. You just won a million dollars.
There may be as many players attracted to the potential glory this gig offers as there are players attracted to the prospect of large prize pools. Ask a hundred poker pros if they'd take a pile of cash over a WSOP bracelet (poker's version of boxing's championship belt—all the glory, none of the brain damage) and almost all of them will say "no way."
There's a large preoccupation with legacy in the annals of poker history. There's really no higher achievement in the sport (if it can even be called that) than getting that bracelet or having your name engraved on the World Poker Tour trophy.
Well, it'd also be nice to win an Oscar, but for most actors, that's not going to happen. You can strive for glory your entire poker career and never achieve it. Yeah, you might win a tournament here or there, but winning the big one is just like every other aspect of poker—a little bit of talent and a whole lot of luck.