My family has learned this lesson. My mom and aunt have been dealing with my grandma (who passed away in September), my 91-year old grandpa, my great uncle who is having walking/balance issues, and my brain damaged aunt. We moved my great uncle into an assisted living place at the beginning of 2018, cleaned out his townhouse and sold it only to have to do the same thing to my grandpa and my brain damaged aunt over the past couple months.
My parents say they will be down-sized in a condo or one level townhouse well before they are 80. Honestly, probably before 70.