eBay has saved a lot of hobbies. I can get vintage bike parts that were unavailable 20 years ago because they were in someone’s shed and they had no way of finding a buyer.
There will always be people asking the earth for junk but you mostly see it listed over and over again because no one will pay it.
An item is only worth what people will pay, if you are complaining because parts now cost the maximum of what you will pay rather than a fraction of that then, unfortunately, that is the way markets work. If they have it and you will pay then it sells, if you will not pay but someone else will then it sells. People seem a little bitter because the seller is now getting the best price for their item.
A wider market has pushed costs up because we are all chasing an ever decreasing quantity of stuff and competing with an ever increasing amount of people who want it.
If you think RC is bad then look at the vintage bike market. Cars are out of reach for the middle range investors so bikes are the new favourite. Money is making nothing in the bank so people are buying “stuff” instead.