Why aren't mathematicians the richest people, if gambling is all probability?

They are true.They call themselves casino owners or lottery operators to get away with it.

The amount of money they can make is dependent on the amount of luck they believe in.

Simple, that's what it is.Gambling is all likely.Even if you don't know the odds, casinos are designed so that the house always has an advantage.It is always the case.One gets no leverage over losing odds by having a deep professional knowledge that the odds are never in their favor, even though anyone could get lucky and come out ahead on any given night.