You have to stay in comparatively lame places most of the time, especially if you want hook-ups. Trailers are really expensive, and then you have to pay a bunch of money to park it somewhere that’s not as good as somewhere you could pop up a tent in half the time for free or far less money.
To me, camping is about experiencing the outdoors, seeing the stars, smelling the fresh air, etc. Trailers mute all of that and is more like trying to recreate home in some lame dirt parking lot that might have good scenery if you’re lucky. They’re a terrible investment unless you go A LOT.
My parents have a $60k trailer they use once or twice a year. I simply rent a $75/night cabin mere feet away from them as there are almost always cabins at most RV places with hookups. They spend tons of time prepping the trailer, and doing maintenance. We just walk our stuff in to a cabin or pop up a tent quickly.