Of course there is only one person in this world better equipped to answer this than me, and of course, that's Phil Ivey, considered the best poker player in the world...and now maybe the best casino cheat as well. Unfortunately though, Ivey is not sitting next to me right now, and if he were, I doubt that he'd be inclined to answer. So I will have a go at it myself, since I do know something about each of those avenues that lead to riches.
Of course the answer is that high-level casino cheating is more profitable than high-level poker-playing, and of course that applies to the professional ranks of both, with the exception of the creme de la creme poker players who rake in millions from endorsements and online poker-room ownerships.
Let's take Ivey as our prime example. First off, it is clear that in his poker-tournament career, he has not earned the $20 million he is said to have earned by cheating casinos via the defective card-cheating process known as edge-sorting. We have heard of two $10 million-or-more wins for Ivey by way of cheating, and I'd bet there are more that have been hushed up. Of course Ivey has probably earned tens of millions thru his endorsements and associations with online poker-rooms, but his entry into this type of "soft" casino cheating was probably propelled by thrills and the knowledge that he'd never be risking criminal prosecution. By soft cheating I mean the type of cheating that does not alter the outcome of the deal of cards or use any type of gadget, electronic or not, to gain an advantage over the casino.
So now to leave Ivey and look at other huge casino-cheating scams, we have seen several raking in huge amounts of money, each one more than any professional poker player has ever made playing tournament poker. There was the $40 million arranged-cards scam that beat Australia's Crown casino, and the huge baccarat scams that have beaten the hell out of casinos all over the world. All of these are much more lucrative than playing poker at any level, and the motherlode of money comes over the course of days if not hours.
However, there is one tiny thing that must be considered by anyone considering giving up poker-playing for casino cheating: THE RISK!
I highly doubt that Ivey will ever be prosecuted for his edge-sorting scams but one day we might see some law-changes by which he might be.