Actually, I'd love to replace some of my velour leggings - but they don't carry those. I've literally worn them out.
I'm in my '60s - and have been able to turn heads in a pair of "stretch pants" or leggings for over 40 years but couldn't find anything on either site that I would buy.
There were two basic styles that I would consider - one came in black, blue, orange and fuscia. The other came in about a dozen colors, all most all were jarring and would not go with my wardrobe. In other words no real style or design that would appeal to a genuinely sophisticated market.
So - the trash niche and they young and unsophisticated market has to be big enough to support them, and if the clothes are not of good quality they won't get repeat customers.