Your specific statement was “But it is completely WRONG that EVERYTHING wears out.”
and then “But the engine is not. It would be a horror if that were the case.”
I’m not sure what you had implied with this, it seemed to me that you were implying that we shouldn’t have to have any wear or maintenance costs for engines because they aren’t a wear item.
First, engines are a wear item, that’s why they need to have a major overhaul every 1,200 to 2,000 hours. Note that the maintenance system does have a wear rate indicator so does model that some things wear faster than others and engine is supposed to be slower. Sure, it says “new” after you maintain but I always just read that as “like new.” After a major overhaul engines are generally considered like new. Most people won’t value a complete engine replacement (and this does happen sometimes at the overhaul maintainence time) and an overhaul that much differently.
I do think there is some modelling of wear rate based on how you use the function. Turbo prop and jet engine planes in real life can wear much faster if you run them too high for too long. I suspect that some of that is modelled here. On the 208, I was maxing the power during takeoff and having very high power during cruise. I was notice the engine wearing a lot. I read the POH for the plane and it indicated that you shouldn’t actually max the power for take-off and also have lower power for cruise. When I changed the style of take-off and cruise I found the wear rate slowed down significantly. I think it’s very good that they modelled this aspect.
Now like everything in the game right now, it may be bugged, it may go faster and the wear rate may still be too quick even if you fly properly. I did say in my original post that I thought engine wear might be a bit fast. However, if you are finding that you need to maintain the engine every couple flights then you may want to check how aggressively you are using power on the engine and see if that can improve the rate.