It's usually the other group that's doing a Motte and bailey here. The billionaires were and are actually quite specific and up-front with their space ideas. It's the media (traditional and social) that invents fantasies here, either to sell or discredit the ideas, depending on which way the wind is blowing.

(As is the case here. We're in the middle of "let's tear down Elon Musk" phase right now, so the strawmen are getting impressively absurd.)