For one, finance is a macro force multiplier; it can make or break entire other industries. There’s also a bit of selection (global top) and survivorship (plenty of less visible non-success stories) in the wild money stories you can see out there.

> family doctors

they can only scale at most linearly, with the number of hours they work.

A financier can scale multiplicatively, because the amount of the monies they deal with can increase without "extra work". The multiplicative nature means the more capital you have access to, the more money you get to make, which approaches exponential at some point.

And in the end, the financier speculating on the markets can affect many more people than the doctor ever can in their life.