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to say that he won't succeed in these grand visions; I think he will, but fundamentally his success is based on taking outdated, slow moving industries and taking them to the next level.