Are you sure it's not just good marketing?

Can't it be both?

Honesty has phenomenal draw in marketing when the recipient agrees with the message. Even if one's disagrees, the product is harder to attack when everyone around it is honest.

I feel like this is one of Musk's greatest strengths. His bread and butter is taking slow moving industries (see: rockets and cars) and coming in with smart people with a framework to succeed. As a marketing ploy, he then sells his grand vision (going to Mars, all self driving cars). I don't mean to say that he won't succeed in these grand visions; I think he will, but fundamentally his success is based on taking outdated, slow moving industries and taking them to the next level.

Why would he try to hide his motives? He has made it very publicly clear that his only life goal is to colonize mars to "save the human race".