We don't have the will power or the resources to do it.
Exactly. There are too many selfish people today who have no clue what it means to commit themselves to something more important than themselves. Try to do a big project like Apollo today and it would be wallowing in lawsuits before the first year was over. People would be on the internet and cable news making all sorts of allegations just to enrich themselves. They'd probably have to make the rocket gantry wheelchair accessible. PETA would demand that the astronauts meals be meat-free. And then there is the carbon footprint of those Saturn 5 rockets!