I don't know, I think comparing anything Balmain, or any designer RTW for that matter, to a vacation home, luxury car or diamonds is far fetched.
Cars aside fashion is the only other luxury item that decreases in value from the moment it's purchased. Yeah, Balmain's having a moment right now but there's no guarantee that any museum will care about curating vintage Decarnin 20 or 30 years from now. Really the only kinds of clothing that will doubtlessly rise in value is haute couture, and the bottom line is that Balmain and couture are in two different stratospheres.
And diamonds? Well, I believe the tagline is that they last forever. You can't say that about a bedazzled cotton jacket or a shredded mini dress.
No amount of rationalizing will change the fact that a huge number of people come in here with Balmain on their minds. Clearly that means that to the average fashion-lover there is a huge discrepancy between the clothes and the pricetags they carry. It's all subjective, obviously, but if so many people feel similarly maybe there's some truth to it.