Somehow I think Elon Musk has made it through the middlebrow dismissal phase of this if the concept has made it this far(to include actual digging in SpaceX's parking lot even).
Musk's a sales technique to promise the moon (Mars really) and then use the cash to build a revolutionary but realistic company.
SpaceX isn't going to colonize mars, but its putting satellites in orbit.
As absolutely insane as his goals are, betting against him overall tends to be a losing bet. I'd be careful about what you think SpaceX "isn't" going to do. If it is technologically possible, they will do it. Period.
And X.Com didn't become Paypal. Paypal became Paypal. Paypal was already developed before the merger and it was not Musk's idea.
Next up: Elon's Space Elevator! Elon's Fusion Reactor! Elon's Teleporter!