I think humans becoming immortal would be awful. Think about the people who would want to live forever. Awful, bigoted old farts in government would never die and progress would stagnate.

#science

There are lots of things I thought would be cool to do, but I never had the chance to attempt, like learning how to play the guitar. If I had unlimited time, I'd get to do all these things.
I also believe there are enough people who'd contribute in meaningful ways to humanity as a whole. Bad people tend to meet a bad ending eventually.