Why does Elon Musk hate the Moon?

I have read a lot about everyone's obsession with Mars. Its cool, its a big red planet months away from us. I don't understand why they push to explore a planet so far away. Why not start on the Moon? It's been done, yeah we humans went there 40 some odd years ago. It's an exhausting three day trip. It's inhospitable and cold and so very close. Why not learn how to survive in such a close place instead of mounting an obsessively expensive mission where the odds of it being a one way trip seem to be extremely high. I am excited that SpaceX has figured out how to re-land their rockets but why not use that technology and put it to better use. The Moon has a gravity that is a third of what is on earth. Doesn't the math show that one of his reusable Falcon rockets would go 2/3's farther without any modifications if it was launched from the moon. Wouldn't everything be easier if we designed a Lunar habit that was specifically designed to make everything that is need for the journey and use it as a staging area for the Mars mission. I don't understand why there isn't more discussion on planning a Lunar colony that can end the end teach us a lot about what we will need to mount a succesful mission and it's only three days away.