The oversimplification makes sense when the side hustle scales without requiring more time. If he expands his vending machine, lemonade, beach house portfolio,

The oversimplification makes sense when the side hustle scales without requiring more time. If he expands his vending machine, lemonade, beach house portfolio, it quickly becomes a full time job, and he will probably need contractors/employees. The opportunity cost of his MD income versus his hustle income will be high for many many years.