It's true that this might not succeed, but it is at least clearly legitimate I think and not a scam, like that flying car from a while back. Certification adds a huge amount to price, as does the premium from being aviation (like how horrendously overpriced Garmin avionics are). This does not use Garmin avionics but rather an iPad and their own in-house displays (obviously the actual panels are Samsung or whatever) so that results in huge savings, especially for the experimental version. So that does help things, cost-wise. But we'll see.
The non-refundable deposit is just like Kickstarter; you're effectively investing in the company to help bring the product to market. It is obviously not for anyone that would miss $100k but there are plenty of rich people that won't.