Like every generation that's retired, ever?
Economics
Seriously. What was the alternative?
They couldnt find one that would only benefit them...
The alternatives are usually closing down and liquidating, or selling to a competitor.
If the assets are worth more than the customers, liquidate. If the customers are worth more than the assets, trying to sell to a new owner or a competitor.
Giving it to the next generation in your family.
Plenty of people don't have a family to transfer a business to, or if they do, that family don't want to be doing the same job their parents did.
I know media want to hype up a "great wealth transfer" between generations, but the consolidation of wealth continues regardless of generation. This won't change the fortunes of the vast majority of millennials.
"Boomers are cashing out their businesses, leaving hopefully millennials deep in business debt."
Either that or they already had money and it really isn't a wealth transfer.