Money
Dr, medications, hospital stays can be very very expensive. My 88 year old mother fell and ended up spending a month in the hospital + 2 weeks in a rehab facility, total cost just under $500K. Why so long - bad reactions to medications and difficulty treating old broken bones. Elderly people get to a point where they aren't able to take care of themselves. You either need to be with them 100% of the time or they need to go into a skilled nursing facility - which costs $10K and up per month. In order to pay for the skilled nursing facility the parents end up having to liquidate all their assets. As a child you feel guilty that you can't take care of them yourself (they took care of you once) and the guilt that everything they worked for will be gone and not passed down to their children/grandchildren.
It also hurts to see your parents not be able to do things they used to do, like not keep the house clean, drive the car, go out to a restaurant, go to church .....
My mother has both Alzheimer's and osteoporosis. She wears depends, can't remember my name from one minute to the next, can't stand for long due to pain, can't do anything other than go from bed to the kitchen table and back. Eyesight is so bad she can't even see the TV to watch it, can't see to read. Because of the osteoporosis she is in so much pain she is only comfortable laying flat on her back in bed. My father takes care of her now, but at some point he may no longer be able to do that. They live in Colorado, I live in New England, oner brother lives in Alaska and one brother lives near them - but works 40+ hours a week.
My advise to you, live hard, play hard, die young. You don't want to get old - it isn't all it's cracked up to be.