Syd was always weird, I think that the drugs just made him too weird for this planet.
Look at the early Pink Floyd hit Arnold Layne...those are STRANGE lyrics, even though I really like the song.
Also, the song "Bike". That is weird stuff, even for the 60's.
A kind of demented genius, I guess. I will say that his replacement by David Gilmore and the majority of writing duties being passed to Roger Waters certainly made Pink Floyd what it became.
I think if Syd would have stayed sane and in band, we would not have heard of Pink Floyd again.