Why it sucks to get old

I helped my dad take care of my grandmother for years, sometimes she was ok, then there was other days that she was mean.
Towards the end she never recognized me, but she would call me by my dads name, or my grandpas name.

My dad is now 75 and he bought a house across the street from me.
Just so he could have somebody close if he ever needed it.
He still gets along ok, but his driving is starting to scare me.