Luck and/or violations of civil/criminal law (e.g. tax shenanigans, shortcutting regulations in things like contracting/plumbing/etc., and so on).

Blue collar grinds to wealth are mostly fantasy. There is a large amount of luck involved: friends/family helping build the business, market conditions, location, etc. That hard work is also required doesn't mean luck didn't play a role (and outsized at that).