I hope no one believes this, but apparently one guy did.
I suppose you can find people who started a business, made it big, said "OK, I have enough," and then retired to a contented family life. Not many, though. Most of the time, they tried it, got bored, and went back to work. Maybe they poured their energy into passing it on to the next generation.
Entrepreneurs are just wired that way. They're addicted to the game.