RIP Syd! I often wonder how the band would have ended up had he not been hooked on LSD (I think that's what it was) and Dave had never taken over his role. Wasn't he sort of forced out of the band?
From what an old friend told me who was the most knowledgeable Pink Floyd fan I've ever known, Syd fell into the LSD trap and couldn't function in the real world. Later as he got progressively more addicted he wasn't capable of contributing in the studio, to the point the band realized they had to do something. I remember two of my friends taking a holiday in Hawaii over 25 years ago now. They went to check out the "Kona Buds" and beaches and night life. When they were in a bar one of them bought two hits of LSD, the blotter had a Purple Dragon stamp on it. Seeing they had no luck finding Pot to smoke, they took the acid the next day. It literally scared the shit out of both of them for life, they got so spaced out one of them didn't think he was ever going to land and feel normal again. After that experience neither one of them would ever touch any of the hallucinogen's again. I can just imagine how much damage a person could do if you take LSD for a long time, eventually you never do regain the ability to come down and live in the normal world, and that is what I think happened to Syd Barrett.
But as previously mentioned, David Gilmour who was a lifelong friend took care of Syd, making sure he was never lacking for money and enjoyed a good standard of living. Very sad but all too common in the rock music world, even today it's not much different.