And how often does your average person need to pull 5 tons of stuff?

Some average people own cows. Others camp in fifth wheels. So it depends?

I'm in my van right now, out on some BLM land with others parked in most directions. The fifth wheelers can ONLY be hauled by a truck because of the way they are designed. Regular hitch-pulled trailers come in all sorts of sizes, and over the weekend we were parked next to two that got pulled by SUVs.

But sure, I take your point, there are legitimate, "ordinary" needs to pull a lot of weight sometimes. The question is whether the frequency of these really justifies this sort vehicle being someone's daily driver.

I know a man who retired into a fifth wheel. He doesn't move it much, but it's definitely smaller footprint housing, so more responsible than most when optimizing for environmental impact. You'd definitely want a truck if that was your lifestyle.

Fifth wheels are just a specific type of pull-along vehicle that connects to the mount in the bed of a pickup truck.

There are many pull-along vehicles ("campers", "trailers") that offer precisely the same space and features as any particular fifth wheel, but connect to a regular ball hitch instead.

At least that is how I've learned the meaning of this term.

Well, this guy has a fifth wheel, so he needs a truck to move it.

Who said my truck was my daily?

OK, so the adjacent question is about the sustainability of everyone (or a lot of people) having a 10k lb-hauling vehicle sitting around in addition to their daily driver.

Once or twice a year offsets the inability to do so.