My father went down hard with Alzheimer’s/dementia 6 years ago, but we still care for him and he still finds things in life to enjoy...even if he barely understands them. He is 82 now and we don’t find caring for him to be a burden. It is a cherished responsibility for a man who gave us life.
It was hard to watch him decline at first...but after awhile, you realize that it is just a part of the cycle of life and caring for him now is as much my responsibility as his caring for me as a child was.
My wife’s mother lost her father to suicide when he made the choice to end it rather than be a “burden”. But he was totally wrong. The burden of dealing with him checking out early was far harder on his children than the years of caring for their mother in her final years ever was.