I have no illusions that I'm particularly useful or contributing anything to the world and just plan on passing the time until I die.
I think it's funny that more people can't accept the truth about themselves. It's not a bad thing being useless, it's just reality for a huge number of people, myself included.
I'm not sure there is a great answer here, so I'm just going to post the Alan Watts talk that brings some perspective for me.
Alan Watts - Music and life: https://www.youtube.com/watch?v=ERbvKrH-GC4
"[..] but we miss the point the whole way along, it was a musical thing. You were supposed to sing or dance while the music was being played".
it isn't so much not being useful but being idle with nothing to do which isn't the same thing