For me, it goes the other way: I know I'm not attractive, and I also know that nothing I can buy is going to fix that, so I buy way less prettiness-related stuff than most people.

I mean, there is definitely a financial incentive to keeping people who actually are attractive insecure. If you convince people that they are certainly hideous naturally, but if they only buy nice stuff they will be more attractive, it forms a very lucrative loop: attractive people believe they aren't, buy nice stuff, expect to look better, and since the problem all along was in how they saw themselves, that expectation of looking better means they actually can acknowledge their own attractiveness.

But if you try that enough times and it never pans out at all, after a while, you drop out of the loop. So, my point: this loop is a real thing, but, you know. Doesn't work for everyone. Get on that, marketers! There is an untapped source of cash here!