Many people have a sense that they could perform much better, given the right opportunities, the right environment, etc. In software development, the thoughts might be: if only the requirements didn't change, if only the codebase was more modern, if only the architecture had been designed with more foresight so we didn't have to shift the architecture while we were adding features. If only I wasn't being held back by these factors, I'd be performing brilliantly. And these factors have nothing to do with me. So don't I deserve to be paid and respected like a brilliant performer?

Conveniently forgetting that the people who perform brilliantly under actual adverse conditions have to be a lot better at the job, and work a lot harder, than someone who feels that they could hypothetically perform brilliantly under hypothetical ideal conditions.

I've never seen someone like this turn to embezzlement, but I've seen them aggrandize themselves into positions of respect through sheer confidence and then bounce from failure to failure, shifting blame to other people or external circumstances.