Self serving or morally gray characters that obtain powers?

Looking for a book where the protagonist gains some type of power(supernatual, magical, telekinesis e.t.c) and primarily uses it for their own gain and selfish/shallow reasons.

It can have a good or bad ending! It's not important that the character learns any lesson either, but I would love some sort of character progression for better or worse. I do want some depth! Nothing too pessimistic or edgy for edginess sake if that makes any sense.

I'm more interested in a female protag but it's not mandatory if you have something in mind that fits. Stephen King has already been recommended a ton as well!