He was the second funniest stand-up comic of my generation. But now he's s tired old man desperately fishing for laughs and usually failing miserably. It wasn't worth it. By comparison, Richard Pryor, the funniest stand-up of our generation, is suffering a chronic illness that prevents him from performing. On one level that's sad and depressing, but it's also good to know we'll always remember him at his peak, instead of as a washed up hack doing inane commercials for long distance service.
People handle deterioration differently.
By contrast Janet Reno, displaying the same symptoms, comes across like a scared, cornered Pekinese. Some people seem immune to deterioration. Aretha Franklin was recently featured on a TV special which included a clip of her singing opera, filling in for Pavarotti. She sounded operatic for about three notes, then hit a note that was pure Aretha. Most artists don't know when to quit and dilute their legacy by putting out miserable, inferior stuff in their last few years.