I've seen two sorts of that kind of founder: some are just excellent and create 20 businesses each of which would be impressive on its own. And profitable.
The other: vast networks of companies all dependent on each other. When any one of them gets in trouble, it all comes falling down like a house of cards. And the chance of none of them getting into trouble? (1 - 0.<failure rate>)^<# of businesses>. That gets very small, very fast.
Lesson: never ever make a decision for business <b> because you also own business <a>. Too many people going from millionaire status to personal bancrupcy, at just about the moment where they're too old to start fresh, yet too young to coast.
It is a better lesson though. Plenty of small to medium businesses fail when their main supplier or something goes under. For a small restaurant this could be as simple as making sure that you have two sources of that special berry (or whatever) you put in your signature dish.
The other: vast networks of companies all dependent on each other. When any one of them gets in trouble, it all comes falling down like a house of cards. And the chance of none of them getting into trouble? (1 - 0.<failure rate>)^<# of businesses>. That gets very small, very fast.
Lesson: never ever make a decision for business <b> because you also own business <a>. Too many people going from millionaire status to personal bancrupcy, at just about the moment where they're too old to start fresh, yet too young to coast.