The eVTOL startups raised $15 billion and got the headlines. GE, Rolls-Royce, Pratt, and Safran hold three times as many US electric-propulsion patents, and every one of them keeps a turbine burning.
Kurzweil predicted nano-fuel cells and microwings. We got lithium-ion automotive packs and FAA Stage 4 type certification — same destination, wrong chemistry.