This quote is taken from his book "Where the Money Was," in the chapter "Sutton's Law."
A few sentences before the quote, he says of the other "because that's where the money is" quote:
I will now confess... that I never said it.
He then offers an explanation of his actual motives, beginning with the text you quote. We can improve the context by reading further:
I enjoyed everything about it so much that one or two weeks later I'd be out looking for the next job. But to me the money was the chips, that's all. The winnings. I kept robbing banks when, by all logic, it was foolish. When it could cost me far more than I could possibly gain.
He is indeed comparing money to chips won in gambling, and "that's all" - not a means to a life he wants, just a thing he gets as a result of chasing the thrill.
He reinforces this idea in the next paragraph by discussing his motives for breaking out of jail. While freedom is the obvious motivation, he again focuses on the action and the attention of the moment, rather than the result of success.
If any enterprising reporter had ever asked me why I broke out of jail, I suppose that's what I would have said: "Because I was in." But also, you know, because there's a thrill that comes from breaking out of jail, after years of the most meticulous planning, with everybody watching you, against all the odds, that is like nothing else in the world.
TLDR: He compares money from bank robberies to chips won gambling, but says it's not the reason he kept robbing banks.