to return a profit on the investment required to service the market.

That's the fundamental stupidity of most of these schemes: it isn't enough to design a paper rocket which may make a nominal profit per flight... you have to find a market large enough & a system reliable enough to generate good internal rates of return to induce an investor or investors into carrying a massive development cost; which in this context probably means (at least) a dozen profitable flights a year for at least a decade. By contrast: MIRCorp found exactly two customers in a year; & even though it had no development costs to meet, lost a fortune.

I wish these vaporware proponents would do some basic market analysis before they started issuing press releases.

Robert