Until we start mining other planets, pretty much all space missions are going to have a huge costs on precious resources either directly or indirectly. We are basically hitting the point of no return if we haven't already passed it when it comes to destroying the natural balance on our own planet, and when things get bad here on Earth, leaving to civilize space or another planet will be reserved for affluent. Right now we are basically just helping them accomplish that goal for them to one day say... "So long suckers!"