One-off models with difficult to reproduce flight characteristics (well documented though), in some cases too difficult to fly for the casual pilot and if there's nothing spectacular about it (i.e. X-15), nobody cared even back when the real thing was flying.
That's no potential for a good return on investment.
Let me tell you a little secret.. It's not about you. Nor is it about me or any other dev out there. It's about the community. Return on investment Pffft. No dev in the history of flight sim has ever made a profit doing this. we always work at a loss. So its not about return on investment. If you want return on investment, invest in oil and tobacco and weapons of mass destruction..
You gotta think globally, not selfishly. Theres no part of any aircraft modeled today that isnt held responsible to the truth. We no longer have the make believe panels orf Mike Stone and others that were thrown together to fill a need with little more than " that looks cool". Aircraft are researched and modeled to such exacting tolerances today it isnt funny: hundreds if not thousands of hours of research alone before the first number is typed or the first line drawn.
This isnt about the developer. It's about the community and providing a platform for that community to experience and enjoy flight in ways that are unprecedented and beyond any experience available anywhere but in actual flight.
So why were the Russians so bloody successful, with the SU-47 where we failed miserably with the X-39? Yeahh, you can read what some junior analyst who doesnt know snot from shinola wrote. That'll give you lots of nice sterile assumptions to go on. but you still wont know Jack about it, and you wont have experienced anything that will bring you closer to that knowledge. You just have something written down thats most likely wrong anyway. You wont know till you do it yourself.
X-Planes, challenge the boundaries of science. Prototypes challenge the boundaries of engineering.
THEY WEREN'T MADE FOR THE CASUAL WEEKEND FLYER!
They arent made for the casual sim pilot either: the guy or gal who wants to take up their cessna cardinal and sight see the back roads of the black forest or enjoy an afternoon tootaling around Cabo San Lucas. These are for people with questions who wont accept some wrote equation in a book buried in the archives of some warehouse in the middle of a cornfield somewhere as an answer.
It's not about you and its not about me. It's about the community and the service we are in the unique position to provide to it. It's maybe even about tomorrows engineers But mostly, its about the smiles.
A Great man, a truly great man by the name of Red Skelton, used to finish each of his tv shows with the statement: "And If I've helped just one person smile tonight, then I've succeeded".
Good words to live by..