@ Seamus and Rotorgun: I don't see space travel developping before there's really something out there worth our time, effort and money. The people financing those endavours will probably remain on earth and would want something tangible for their money. The people leaving would need a really good reason to leave. Remember that the 'new world' back in the age of discovery was a pretty nice place to go and live, Mars ain't.-doc_bean
Just let one of our probes discover something really valuable in large enough quantites to justify the expense, and it'll be "Katie, bar the door" in the efforts made to get there first. Imagine the gold rush of 1890. There were plenty of folks willing to risk life and limb to attain the "mother lode" and thereby gain a lifetime of wealth. As for those who would want to live on Mars, I agree that it is beyond the scope of most people today, but it is seriously being considered by some pretty smart folks among the worlds space exploration community.

Heck, I might even want to move there if I wasn't so old and tied down with the cares of my life. At least I would get a little peace and quiet for a change.