PBS had a special on Johnny Carson's life in 2012. They interviewed friends, other comedians who knew him and even one of his ex-wives. It was a fair and fascinating glimpse of a man who was immensely famous but increasingly private. He had 4 failed marriages (he and his last wife never divorced but they ended up apart), he was never close to his sons (his middle son was killed in a car accident on the Southern California roads), and at the end of his life he had about 4 friends left. He was a serial womanizer and he spent much of his last years sitting on his back porch in Malibu staring at the sea. He really did become a hermit; probably a natural situation for a man who could never have privacy any other way.
He battled alcohol through-out his adult years; turns out he was a) a mean drunk and b) had bigger problem than Ed McMahon.
Emphysema took him at age 79. He chose not to fight the ravages of the disease caused by a lifetime of smoking.
He was generous, gave many people or organizations monetary gifts; and left $156 million to be distributed; a sizable amount.
He died, rich, incredibly famous and pretty much alone. It was a sad ending.