I realy don`t think this guy was as mentally ill as people believe. When he was in Pink Floyd, it seems he just took too many drugs, especially LSD which basically makes you act schitzo. Then when he left them, he put out solo albums and then seems to have quit the music biz in favor of painting and gardening. I really don`t think the guy was as nuts as people believe.
I mean doing that music thing is not for everybody, it is very stressful in a lot of ways. You`re under a contract and have to coninually put out new material, tour, you have liberals all around you constantly, especially back then in the `60`s and `70`s. He could have just quit because he hated it. There are tons of musicians who did that, who played for a few years then completely disappear.
Awesome that you can make detailed psychological analyses from a wikipedia entry.