@TuringEquivalent,
Cryptography involves a lot number theory and abstract algebra, doesn't it? And in data security applications there is, at the very least, some of the same type of creative, what-possible-moves-might-my-opponent-make thinking that is required, say, in writing adversarial arguments that provide lower bounds to computer science problems.
Therefore, I think data security might be your best bet. Seems to me there's more creative problem-solving, generally, in IT careers, than in finance.
(My answers are all so much speculation. I myself would love to hear better answers to TE's question.)