1. Actually, we don't have everything we need yet to do this. We're not even capable yet of sending humans to Mars.
2. We COULD be at that point by now, except we're too busy squabbling amongst ourselves to make any effort towards space exploration. The only reason we went to the Moon is because of the Space Race/Cold War. Now that the world's superpowers are distracted by other things, very little progress has been made...
3. To everyone saying colonization is a bad idea, it's only bad if we discover an alien race and try to conquer them. Uninhabited planets can be made inhabitable with the right technology (the "Red Mars" trilogy presents some cool theories on how we can make this happen).