In reply to NickD :
I am a huge fan of historical aviation, especially WWII era, and I would much rather see them flying than in museums. Although, I would agree, those who fly them (or any plane) without following FAA regs on inspections and maintenance (there are a lot and are WAY more strict than what cars might have) are doing a great disservice to everyone involved.
Probably my favorite "museum" is the Chino museum in CA, and they are very focused on getting the planes flying. While it is great to see an actual plane in person, seeing, and hearing, them fly is an entirely different level. They are currently (about to?) get the US's first jet powered fighter (Bell P-59 Airacomet). I would very much like to see that fly!
Of course, many of these planes, especially WWI and WWII fighters are historically VERY prone to accidents. Most of that of course was the result of throwing 19 year olds into high performance planes, but, they are generally not optimized to be easy to fly, just to fight.
As an example of a great loss, Chino did manage to get a Northrop N1-M flying, which was a prototype development for the flying wing planes. I did eventually crash (engine issues, which as you can imagine, losing an engine in a small flying wing is a huge issue), but I am very happy to say I saw if fly numerous times, which was very cool to see!
Regarding Reinbeck and the WWI planes (which I haven't, but I would love to go see, and hear, them fly!). Those planes are very very "hinky" in how they operate (e.g. essentially no ability to steer once on the ground!). So accidents are far more likely (though generally at very low speeds). WWI plane though are also very basic in construction (e.g. no way you will have a flyable mostly original plane!) so are effectively super easy to rebuild. Almost the same could be said for some WWII planes (but they would need to be very valuable). Many cases of planes being effectively build from data plates (essentially VIN tags), which almost every part either replaced or rebuilt.
Rebuilding and even re-creating these planes only becomes easier with the advances in technology machining.