Spot on. A VC will fund something really risky and innovative if and only if they think they'll likewise make a larger profit from it compared less risky ventures. But as pointed out by other commenters even this risk-taking is limited.

Ventures like SpaceX and Tesla that have a long lead time and (at least in these two cases) are loss-making at the start probably wouldn't get YC-VC funding. Or at least they wouldn't get anywhere near the level of funding they'd need to get to profitability point.

I wager that for some of the really big world-changing projects we simply have to be willing to fund it as long as necessary, taking an extremely long-term view. And for this, VC funding is probably not going to be enough. Both Tesla and SpaceX needed to take in public (read: Government) funding to keep going.