I would say it's similar to not using the same password on multiple sites.
If you use the same email, once that one is compromised, than all accounts related to it could be in jeopardy.
By having a separate account just for financial purposes, which isn't used for regular emails with anyone, it just decreases the chances of it being leaked.
Is it really cronyism? It seems like most of the "qualified people" don't share his vision, so why would you hire someone that is so opposed to what you're doing?
If Trump were a Silicon Valley CEO, we would be saying he's not hiring them due to a "cultural fit."
If you use the same email, once that one is compromised, than all accounts related to it could be in jeopardy.
By having a separate account just for financial purposes, which isn't used for regular emails with anyone, it just decreases the chances of it being leaked.