Bayesian reasoning? How many times do you touch the stove before you get cynical and expect hot stoves to hurt?

Desiccant/absorption dehumidifiers are nothing new. I've been around the block enough times to recognize the hype cycle. The motivation of the inventor seems pure, and the first order analysis seems to make sense. Dehumidifiers do indeed pull water out of the air, so it seems plausible that this tech could one day be used to quench the thirst of people living in deserts. The moller skycar scam has gone on for decades in no small part due to how reasonable it sounds. We know machines can fly, so why not a road-worthy aircraft? On the surface it makes sense, so the scam finds plenty of marks. But the devil is in the details.

Aside from the fact that there isn't much water in dry air, 2257kJ of enthalpy is released for every kilogram of water pulled from air and that's a lot of heat to get rid of somewhere. Most mature cooling technologies (peltier, compressor,etc) have a COP value smaller than 1 so in other words it will take even more energy to harvest water efficiently. Trucking water might actually be cheaper.

I recently found out that Opener is getting funding from Larry Page for theirs. It certainly is technologically feasible to build such a machine that actually flies. But the question is, are they making yet another glorified ultralight? Or are they really going to give us the flying car in every garage dream promised to us by the Jetsons?

If they're proposing an ultralight, I'm not too skeptical. Loads of companies have successfully created ultralights. If however they're trying to sell me the dream, like Moller, then more skepticism is warranted. There are a lot of problems with the dream that aren't really problems for limited production ultralights. For instance, the simple matter of how much low air traffic is tolerable to the community. Or the incidence rate of poorly maintained aircraft falling out of the sky and crashing through my living room ceiling.

If these MOF people were talking about more efficient desiccant dehumidification, I wouldn't be nearly so skeptical. But by making it about the noble feel-good mission of drinking water from thin air, they're sending out a different sort of signal. It tells me they're looking for hype, and the way they're doing it has a past association with scams that I can't rightly ignore.

Everyone is building one, but no one has really proven that the market really exists. The cost-estimates I've heard are cheaper than helicopters, but in the same order of magnitude. These UAM vehicles are going to replace helicopters, not your car-based Uber ride.