and talked with them about this topic. First, you are right: RV dealerships are never going to try to convince you that having an RV will save you money long term--they won't. The reality is that RVing is expensive when you factor in all of the costs.
RV dealerships sell a lifestyle: the freedom to see the country on your own terms. Freedom to stop and go when you want. Eat, sleep and use the restroom when you want, etc. The appeal is nothing more than the promoted/promised lifestyle/convenience. You really have to be retired though in order to take full advantage of the alleged "freedom."