Dear Keith,
Hardly. There are, after all, other film cameras than Leicas. If every single Leica user shot 500 rolls a year, it would probably be a pretty small blip compared with the people who are not putting film through their Olympuses, Pentaxes, Fuji point-and-shoots....
Reverse your postulate, and it becomes clear that people are buying MPs because (1) they are among the few new, good-quality film cameras still being made and (2) they last; are reparable; and can handle heavy use. I'm not saying that this analysis is any more valid than yours -- just that both are at least equally defensible.
As for wanting to wear out an MP, why? This is a distressingly common viewpoint here on RFF: "I wanna buy an expensive new Leica and trash it." But a camera picks up more or less wear and tear as you use it: why try to wear it out? A fellow journalist once said of my MP, which has a fair number of honourable scars, "That is an ABUSED camera." Well, no, it's not. It's just a camera that has been used quite a lot.
Cheers,
R.