As an expanding species which won't stop until nature steps in, it's rather in our interests to move off earth.
That said, I don't think his Muskness is the man to do it. While you are waiting for your Tesla to charge, you will have plenty of time to start writing down the reasons why.
I grew up in the 70s, when nuclear fusion was "just 10 years away". Much as it is now.
If you wanted to colonise other bodies in our solar system (because that is all you have so even then your resources whilst considerable are still finite) you really have to start with living on the moon. Not popping up for a month or two and then popping back when you can.
Living
And given the first settlers to the Americas - which at least has air, water, food and shelter - managed to perish a few times before finally establishing a foothold, I wouldn't hold my breath.
How would giving birth and growing up in 1/6th g work ? Bearing in mind anyone born on the moon (or Mars) probably could never come to earth. Mind you, who'd want to ?