I really respected his private life after the band. It shows that we're all special "somebodies"- even the most obscure and forgotten "nobodies".
Similarly, I don't think his anonymity was particularly sad, rather it was beautiful. People act like the man died just because he wasn't some Hollywood phony who did Rolling Stone interviews. He had a life, a nice quiet life for himself.
He had mental problems, and was living with his parents. Did he take all the drugs because he had mental problems, or did he have mental problems because he took the drugs? I don't know, but I pray that my life doesn't end with my 80+ year-old mother taking care of me because my brain is fried. I suspect he had mental problems and took tons of drugs, which amplified his mental problems. The LSD and other drugs may not be the reason he was a basket case, but it didn't help. Apparently, his creative life ended around 1974, when he moved into his mother's basement.
I have a cousin in a similar situation, drinks heavily, around fifty, still living off his ninety year old mother. Before he went doper, he had a tryout with the Cincinnati Reds and a college baseball scholarship. Wasted life.