Instead of spending money and all those efforts in trying to travel to new planets and colonize it, why dont we spend those money into making our planet better to live in and eradicate a lot of problems that we currently have like hunger and poverty.
Why leave the house? I have everything I need here including food/love/work. Human kind has always strive to go beyond its own capabilities. We are taught to dream big and reach for the stars. Hampering that due to nearsightedness or budgetary reasons is what will hamper us the most in the long run.