Fashion isn't the best example for this, because often people are paying for prestige more than quality. A $3,000 purse isn't 100X as good as a $30 purse; the exclusivity of a brand that expensive is the attraction. People who opt-out of this competition however, may instead brag about what savvy shoppers they are.

There is a relevant theory in economics called "the market for lemons" that speaks to what you are saying though. The idea is this: if someone is trying to buy a washing machine as cheaply as possible, they would rationally pick an $1000 machine that lasts 15 years over a $500 machine that lasts 5. The problem, however, is that the consumer often can't tell if the expensive machine is really better quality, or just going for a higher markup. With that uncertainty, it is safer to buy the cheap machine. Manufacturers know this, so they compete on price and features more than longevity. Without a time machine, consumers can't see if the extra money they spend is worth it, so cheap crap is the equilibrium for the market.