I understand. Robin Williams was the first celebrity death in years to hit me like a hammer. Like how Michael Jackson's hit Mentalist.
But in the end, I sort of understand it, because while the news made me extremely sad, I wasn't totally shocked. His comedy revealed all we needed to know about his personality type and his weaknesses (I almost fell into the media trap and wrote "demons" - no more with that word). There are some entertainers whose behavior or remarks or even performance style, give away the tortured artist behind the celebrity. And he was an artist.
As tortured artists go (who inevitably flame out rather than fade away), 63 isn't a terrible run. That sounds cold to say, but look at all that he left us. And he raised three children, all of whom reached adulthood with his loving presence still around. If what his wife alluded to is true, I think it was the onset of Parkinson's that caused this downward turn. I don't think he was the kind of performer who could learn to integrate his condition into his work, like Michael J. Fox.
It's terrible and awful and we may never fully understand it, but we can still embrace a full lifetime's output of artistry as a comfort. For me, it's worse when it happens to someone young, like Kurt Cobain or Jeff Buckley. "What could have been" is such a black hole of wondering to fall into...