Fame usually crushes people's state of mind in different ways. Many can not deal with the price of fame and how it affects their mentality. People around you start acting greedy and everyone wants something from you, you can't be out in public anymore without being mobbed. It really does change people. Michael Jackson's depression and insecurity came from immense fame, while before Thriller he was able to deal with it.
No amount of money or personal success can help depression and insecurity issues.
Lets all remember, that as sad as this is, Robin is in a better place now and is no longer battling his demons. Rest In Peace buddy.