Robin Williams was, arguably, the most fearless artist of his generation in any field in any genre. It wasn't just that the guy knew how to make you laugh, he told you the truth and a truth that was hidden beneath the laughs. People like Williams are able to see the world and see how f***ed-up and absurd and how patently unfair this world is and point out, using humor, that very fact. To be that brilliant at expressing that with comedy, you have to conversely know and have experienced depths and despair and depression. People ask "why would such a funny guy be depressed". His depression was what contributed to his brand of humor. They were different sides of the same coin. Being in tune with his contemplative and dark side was what made him an even more brilliantly dramatic actor (for a truly disturbing performance, try the 2002 film ONE HOUR PHOTO). That dramatic side is what made his comedic side make sense.
This is a guy who has more than earned enough success in his career doing all kinds of films that, at age 63, he should have had the luxury to be a Bill Murray and be able to pick and choose the projects that he wanted to do instead of the projects that he needed to do in order to pay the bills. What is sad about the end of his career is that even the "safe" choices that he was forced to make weren't paying off (how many of you even knew that there had been a 2013 Robin Williams TV sitcom?). Nothing against Night at the Museum and other family popcorn fare. But perhaps Williams wanted more and was frustrated that the inability to have that was out of his hands.
Family popcorn fare was a huge part of his career though and always had been. One of the things he was most famous for.
As he was reportedly worth $50m and had a $35m house to sell, he wasn`t in the desperate financial situation that some are suggesting.