Stephen Hawking was once cited as saying that humans must leave Earth within the next 600 years.
OK, sounds like we have enough time.
His reasons were multi-faceted, all converging on multiple possible doomsday scenarios: AI retaliation, global warming, alien massacre, asteroid collision. OK, all sounds really, really bad, but over population is not a stretch either. Yes we have to get out there. No we shouldn't wait until we absolutely have to before we do - reasonably that would be exercising very poor judgement and would increase the the risk of failure.
Who's going to fund this adventure? Don't depend on your politicians they can't even figure out how to pay the bills without borrowing money. I mean, really.
Best thing to force us to shape up is a (failed) alien invasion. Then we'd all band together and focus on building vessels and technology! Unfortunately, it's much more probable that beings advanced enough to the traverse the stars have the knowledge to bio-engineer very effective means to simply wipe us out (ie: super virus) - and at the same time leave their future assets intact. Nope not one bullet shot.
I think we will be relying on the drive and ambition of our billionaire entrepreneurs just as long as their accountant board types don't ratchet them down. Leaving it to the bean counters and the risk equation will never permit true discovery.
Our problems aren't getting any easier. Just turn on the news from any country and you'll see infrastructure crumbling, debt growing, social unrest, war, famine, natural disasters - quick turn the channel. My answer is don't watch the news.
Where am I going with all this ramble? Pressure. Lots of pressure to solve the problems at home and not spend the money on silly old space travel.
So we need some real leaders to make a difference. Maybe that's you - I don't know. Maybe it's all of us. One thing for sure, we aren't getting off this beautiful green and blue orb by just dreaming about it.
Who really wants go out into a cold, black vacuum anyway?
Turn the TV back on. What am I thinking? Time to check facebook!
OK, so our real enemy is what we call our "entertainment". With enough time, we'll die off, keyboards in hand, but we'll be happy about it. We'll just escape into the matrix (until the power goes out).
Maybe someone should start a new religion - the Church of the stars - those dedicated to ascending and living out there...