I dunno. I know some pretty wealthy engineers (or ex-engineers?) I may even be one.
I think perhaps "engineering personalities" are less prone to massive or obvious displays of wealth, less prone to being driven to acquiring excess wealth ("hey, the problem is solved!"), and less prone to being heavily in debt ("math is a skill".) So, for example, Woz is a lot less rich than Jobs (was.)
particularly compared to the financial professionals?
You mean like "Congratulations on your Wharton Graduation. Here's your Bank Manager job. I'm sure you'll be an assistant junior VP with a six-figure income in no time! All you have to do is NOT SCREW UP" ?? I dunno if it's that simple. But the best way to get rich seems to involve helping other people to get rich as well (or something like that.)
(Whereas an engineer who merely "doesn't scew up" can only expect to earn a moderately comfortable salary doing Interesting Things.)
OTOH, I know a fair number of people whose major callings are Artistic. Singers, Songwriters, actors, writers, photographers. People who are REALLY GOOD, but probably not good enough (in all the myriad ways) to even have a chance of making a living at what they love. The best they can expect is a job that doesn't suck, that will pay well enough (and leave them enough time and energy) to feed their passion a little bit...