What was the most tragic death in the music industry and why?

Has to be Syd Barrett from Pink Floyd. He headed all of their early hits, but his extreme overuse of LSD saw him lose himself, so the other members kicked them out. Then they floundered around for awhile without Syd, until they made started making songs about him (although after Dark Side of the Moon). He retreated to public isolation, but he couldn't get that due to the press trying to pester him constantly. Syd Barrett died at 60 in 2006 from pancreatic cancer, due to diabetes complications.

Edit: Allow me to clarify two things.
No, Dark Side was a massive success. I worded the sentence poorly (I meant their success post Dark Side was based on Barret, not that it came after Dark Side). But anything before then didn't do great. And most of their work that did well after Dark Side was based on Barrett (but not a big amount of it).

And yes, I know he had mental issues before hand, but they only got as bad as they did due to the LSD abuse. Syd would have still suffered due to those issues, but it wouldn't have caused him to lose himself, unlike what ended up happening.