It depends on whether one is a collector or a user; and Leicas are bought by both. I fall into the latter category. My M4-2 and M3 were not particularly expensive, as I bought them used at a good price. I bought the M6 new, and yes, it was a bit of a splurge, but no more than a comparable Nikon or Canon pro level camera would have been.
I did not buy Leicas for the "mystique" of the brand; I bought it because it was the ideal tool for the work I do, which is dance and theater photography. It it silent and unobtrusive, and lasts forever. I consider them excellent investments. I can't afford, nor am I interested in owning, "mystique."