Well, speaking from the vantage point of being 70 years old, I would have to say that "old & useless" is pretty-much how society at large views us older folks. As I have sometimes said: in Asian countries it at least used to be that the young bowed to the old. (I don't know if it still is.) In the U.S. today the old get out of the way of the young.

I live in an area where there are a lot of us "senior citizens". Some older folks find fulfillment in volunteering I guess. It seems like quite a few end up babysitting their grandkids. Younger family members stop by on holidays to visit their parents & grandparents. Then they disappear until the next holiday roles around. Personally... I just keep to myself. I do hope though that, in some way, you are able to find the fulfillment you seek.