OTOH... In the context of a moonshot, maybe the non-existence of an affordable & appropriate engine is ok. Tesla started with an unaffordable battery, and built a really expensive car with it. The car was good though, compared to other cars in the sheiks & princes price range. It was an important step on the way and proved that the real pertinent problem was affordable batteries. Not an easy problem, but still.
There's probably some demand for flying motorcycles, even if they cost >€1m and are only good for 10 minutes of hovering over a lake.
From there... who knows. I'm not sure flying cars a mass market idea even if they cost the same as rolling ones.
I'm not sure if you're trying to imply it, but YC funding defense tech under the guise of funding toys for the ultra-wealthy would be interesting, but I don't honestly think that's what's going on here. I don't think they're likely to develop novel turbine technology, and the concept of a one-person turbine flying device left the US military unimpressed decades ago. There doesn't really seem to be a tactical niche for it on the battlefield.
Anyway... the military isn't always the ideal market force for driving down costs.
> The startup’s most pertinent problem is creating the autonomous stabilization technologies that will make flying the Speeder effortless and safe.
looks like a smokescreen for marketing to the tech crowd. Everyone is going to believe they can solve the stabilisation problem: that's "just software" and we see demos of robots solving stabilisation problems all the time. Building a jet engine that's an order of magnitude better (cheaper, more reliable) than the industry has managed in 50 years, but with more or less the same tech? That's the kind of problem you can't just solve with machine learning.