Just depends what you define as rich, if you want a few million work for yourself( contracting, developer, franchising, vending), Billionaires, primarily emerge out of real estate, tech, retail, beverage, and fashion, and about a 4th from "investment" . Kind of surprised at the richhate here. IDK maybe cause of school but I was surrounded by varying degrees of "rich" and they all had pretty much one thing in common, they worked for themselves, didn't see a lot of trust fund type wealth.
Sadly I don't have the faith to quit my job and franchise something or buy a sales route.