Alzheimers

I was thinking about an old phrase today when this popped into my head and struck me as extremely funny.

Hindsight is 20/20

and then I was thinking of the exceptions to this case. So I said,

Hindsight is 20/20 unless you have Alzheimer's disease.

and then I just burst out laughing. This was very weird because I was at home and no one was there. Am I going crazy?