I'm not missing that point, but the point is moot if the company goes bankrupt. You have to start simple and then expand. The original Tesla Roadster was a conversion of a Lotus Elise; Tesla bought from Lotus nearly fully complete Lotus Elises, without powertrain components but with just about everything else, and then they put in third-party batteries and other components to create their car. They used that income, and the additional investments they were able to get afterwards, to then create the fully Tesla-built Model S. If they had tried to start with the S then they would have gone bankrupt.
Hill should have started simpler using a third-party engine, and maybe even third-party avionics, even though that makes it more expensive, because that would massively reduce the development time and risk and allow them to start shipping units sooner, letting them get actual income as well as more investment when they prove they can create working helicopters. Then they can use that money and time to develop their own engine/avionics.
Nobody in the aviation world creates their own engines. Boeing does not, Airbus does not, Robinson does not, Cirrus does not, etc. It's crazy.