let's thinking about this from humanity's point of view in a thousand years. if someone stopped polio now, his name would be in history. if someone colonized mars, his name would be in history, and probably of bigger importance. because it is a more audacious goal and having higher impact to the future generation.

if you ask me to donate to stopping polio vs spacex, i would probably donating to stopping polio. however, that is because i'm a little bit short-sighted on goals. (incidentally, i guess this is why i'm creating an internet business rather than a space exploration program.) however, that does not mean i should not let other people try the more audacious venture.