> I'm guessing he'd take that money and just privately fund SpaceX
If his goal is to colonize Mars and you want him to sell cars, a good way to do that is to say "sell cars for 10 years and we'll give you enough capital to do in the following 10 what you couldn't do in 20 from today."
If his goal is to colonize Mars and you want him to sell cars, a good way to do that is to say "sell cars for 10 years and we'll give you enough capital to do in the following 10 what you couldn't do in 20 from today."