Hopefully your friend's siblings will step in to help him take care of his parents. Last child or not, it shouldn't matter. So sad to see someone go through all that school to end up not using it due to life circumstances beyond control. Also unfortunate that some kids will forsake their parents until the parents are about to pass away. You can call it karma or whatever I suppose.
I'm the oldest child in my family. My parents have paid their house and cars off and are in good health, so other than taking care of my 2 youngest siblings, they have few financial hardships. We always send my parents $ here and there and when we are visiting them, we take them to do something fun, eat somewhere of their choice, and take them to shop for items for themselves as well as groceries for the family. Also, if our parents ever express they're searching or wanting to try something, if it's in our means we get it for them.
Most of our other siblings that work and live in the same city as our parents already help our parents here and there, too. Most of us siblings know in our hearts they love no one more than the other, although often times some of us felt they are more lenient and paid more attention to the boys.
One day, if my youngest brother or the other brothers doesn't want the responsibility of taking care of my parents, husband and I already decided that we'll take them in with no strings attached just as we are doing with my FIL. Financially, we depend on ourselves. Even though FIL gets social security benefits and offers us $ towards mortgage or groceries, we never accept it, thus we'll extend this to my parents as well.