See, you say that, but you haven't actually given any examples. I went over to fix my neighbour's boiler today: does that display selfishness in any way? She's a decrepit old lady. I was feeling a bit rubbish with a bout of flu. I didn't get anything out of it apart from feeling even worse, tearing a fingernail and having to lug some stuff over from my house. She got out of it a working boiler. I didn't even come out of the house feeling good about having helped her because I've been in such a foul mood recently. How does that make me selfish?
You seem to be equating need with selfishness and treating them identically, which isn't the case at all. I can need something, but not necessarily need it for selfish reasons. Likewise, I can be selfish about something and not need it.
Well, that's just not true. Not everything we do is motivated by a constant, pathetically selfish need for self-gratification. Or at least, not everything I do - I can't speak for anyone else here.
Travelling at the speed of light isn't necessary for space travel, though.