I had an old teacher who died almost a year ago.
Great guy, very sociable, knew everyone in the little town he lived in. Kept in touch with a lot of students. Good neighbour, friendly guy who'd talk to everyone.
He got Alzheimers. He started forgetting stuff, and it frustrated him. He got caught driving dangerously, and cursed the doctor who took away his license.
He argued with me about the state of some chicken he wanted to cook. I told him "this is pink all over, you have to cook it more". He got angry. I understood he'd become like this to everyone.
He pissed off everyone on his street, and all police, medical and social workers sent to help him. The disease made him blow up every relationship he had with anyone that he didn't know well, like me and a couple of colleagues.
He got found in his house, having left the gas on, endangering the whole street. He ended up in a care home, not knowing who he was, or who I was.
If he'd been run over by a car, or died of a heart attack at the age of 80, people he knew would remember him as that nice old guy who had a dog and made a lot of art, and was friendly to everyone. Instead he was that 83 year old guy who pissed off everyone, nearly blew up the neighbourhood, and drove like a maniac.
You really don't want to end up with dementia and related illnesses, it totally sours everyone's view of you.