It's funny, I have also asked that to a lot of people, but I immediately tell them that they will stay young and healthy (but experiences and knowledge will continue accumulating) and that there are enough available pills for anyone wanting them.

99.9% say they wouldn't take it. The usual reason is "I'd get bored".

Then I ask them if the think the majority of other people would get the pill. 99.9% think that other people would take the pill.

I suppose that people really hate their lives, don't dare say that not even to themselves, and they think other people have a much better life.