The OP runs the numbers the right way. For a given rig. But one can start with a clean sheet of paper to come up with a rig that will last a lifetime (such as an Airstream, new or used; ten years is sort of broken in) and match it to a tow vehicle (again, new or used) that is economical to operate over the longest period of time. Say, a decade. The result is a low cents-per-mile fuel cost on a vacation as well as year round.
This approach more than pays for itself. Depreciation is minimized or avoided altogether. And one isn't trading the badly made conventional RV at the average six years. I have less in both my vehicles than most have in either. Even used, in many instances.
At just over fifteen-mpg with a 35' TT behind a 3/4 ton, the particulars speak for themselves. Right inside of other owners with the same basic truck and size/weight/design of trailer 14-16/mpg.
As well, one can learn to exert some discipline in solo use where the TV is also the DD. Given ones annual fuel cost, savings there which do not lose any of the convenience of the DD, but accomplish the same ends with a little foresight and improved driving habits can underwrite vacation travel. I was already doing well in my DD fuel costs, but took this challenge and reduced annual miles to do the same errands, etc, and improved driving skill. Extrapolated out over a year it was a 20% savings. In my case that would mean 5,000-miles FREE VACATION TRAVEL.
Depreciation is the real killer. On both vehicles. Being smart here practically means a free combined vehicle compared to the buying habits of some over just a couple of decades.
And then lack of control over TV use. Lack of awareness over the high price paid for indiscriminate use.
As an RV is also a port in a storm when things go wrong at home -- man-made or natural problems -- I think the subject deserves more than just some emotional wrangling. It's not quite an "asset", but it's worth looking at it as if it were. Long term plans on care and maintenance for both. Treating them better than many do. Etc.