I understand Cher's daughter has always struggled with weight which led to an eating disorder. Maybe giving up the struggle cured one problem and gave rise to several more. I can imagine her having a whole list of psych problems. I'm not laying that at Cher's feet but she'd have been a hard act to follow. Maybe swapping a beautiful woman for an ugly man isn't so surprising under the circumstances.
I understand what you are saying. My ex is the son of a very "big" actor here, and even though he is perfectly equipped as a person with charms, good looks and brains, he always feels inadequate. Like Cher´s daughter, he also has a "hard act to follow". As a result, he has a lot of demons to fight with. It is a big shame, because there is nothing wrong with the "raw material."
The fame doesn´t come for free for anyone involved.