There are certainly people who can take real happiness from that. But I doubt many industries have anywhere close to as much peer pressure as the fashion world.
Most people who attempt to dress at the very cutting edge are doing it because of the immense pressure for them to be at their very best, all the time. It has less to do with their own desires regarding style, and more to do with their desire to be noticed. And I don't mean that in a super narcissistic way (though that's true for some).
I mean that few industries are as much of an uphill battle as fashion is. Most of them are actively trying to advance through fashion culture, and being impeccable all the time has far more to do with their social defenses while they climb that ladder than it does with personal happiness in the moment. And once you have people's eyes on you, you can't stop being perfect. Because the first thing they're going to do is note every single one of your flaws. And when I say fashion culture, I don't necessarily mean actual work in the industry. I just mean the social spheres that high-level fashion is a focus of.
I'm sure some of them DO just do it for pleasure. And most of them (hopefully) don't hate it. But I doubt the fashion itself is the ends for most of them - it's the means to the end, with the end being social status.