We do not need humans in space.
Humans in space may be the only place where there is peace in the future.
Take a look a this old world, and you soon realize that our exiting into space will happen for the same reason Europeans left Europe for the New World.
We do need humans in space.
Eventually our Sun will use up all of its hydrogen, and start expanding. The Earth will no longer be habitable, and humans will have needed to establish independent places elsewhere. The sooner we begin, the better.