People wanted to buy them because they were 'buying a dream' - and helping to move the ball forward.
There was a huge amount of 'good faith' in the process by early customers and supporters. Even to this day.
Tesla is an aspirational brand and people are paying an aspirational premium.
Boom will definitely be that as well. Execs will humble brag about their Boom flights, everyone will talk about - it's super exciting, super cool.
The issue I'm pointing to is scale ... will those smaller tranche of buyers be able to support all of the operational overhead of the airline and the ongoing R&D of the company ... is the question.
edit: I say this as someone having little to no real knowledge of the aerospace industry :)
In the end the product was nothing like the Elise. But intermediate products were like the Elise, and could be driven and test manufactured and could inform revisions. A half complete scratch design could not have been.
... after he bought out the founder(s).
It's the same as some people who say "next startup, I'll go straight to insert scalable architecture". That doesn't work. You need your flexibility to experiment and find what really works in the beginning.