Has any President hired a poor for a cabinet level job, especially and economic one?
It really depends. What about a high paid econimics professor that would be considered "poor" by Trump's definition.
That is what is really interesting about this. Above a certain point, wealth is more an issue of risk than skill.
There are tons of Intellectuals and Civil Servants making 10 or 15 a month who are just as skilled as the businessman making that much an hour or minute simply because they are passionate theory and policy.