Some of the formerly famous do not want to be seen when they become old and frail. Then you get others in even worse condition, who still insist on going out and engaging with the public. Muhummad Ali was that way, Stephen Hawking also comes to mind. The nature of different people.
I remember whan Muhammad Ali was the one who lit the cauldron for the 100th anniversay edition of the summer olympics, frail as he was, in Atlanta. He showed that even with age and challenges, you have to keep going.