I've resigned myself to the fact that most really rich people became so doing things I'd have never in a million years imagined you could get rich doing.
Many of these "I'd never have imagined you could get rich doing... (groceries|steel|lumber|shoes|silverware|bandaids|etc) examples take generations to build the business large enough to actually "get rich." They're definitely not "get-rich-quick" schemes but slow, methodical progress made on capturing a portion of industries with billions worth of turnover per year. Obviously counter-examples exist (Cotsco, etc.) but by and large these stories involve generational contributions to the business.