I know someone who is an accountant for very wealthy people and quite a few seem to have useless children whose failing businesses they bankroll.
Startups are like sports cars nowadays. People think it makes you look cool if you own one.
It doesn't matter if it costs a lot of money to maintain. Yachts and sports cars do the same. That's actually like the whole point of it, after all.
> whose failing businesses they bankroll
Don't confuse a hobby business with a failing business.
Plenty of people with independent means run loss making businesses for fun and/or support wives/children doing just that.