Martingale strategy will lead you to heavy loss, because there is no guarantee that you will win your next bet if you double the lost amount. There is no gambling strategy on earth evented by man that can give you constant win in the long run because gambling is based on luck. The most skillful gamblers on table games will definitely run at loss in the long run because they will never be satisfied with their wins and would continue gambling.
While you are correct of martingale not working (it's proven not to work), rest of your text is contradicting itself in many ways.
I am assuming that when you are referring to skillful gamblers on table games, you are talking either about blackjack or poker, which are the only games that require skill as well as luck. Anyway...
Most "skillful" players wouldn't use even martingale, because that has nothing to do with skill. Nor they would be driven by greed. I am not sure how you even mad that leap, because i can't see any connection. Why skilled gamblers wouldn't be able to quit? It's a part of the skillset to walk away as and accept your losses.