I was in Vegas last year and I saw plenty of that too but you're right. Gucci logo shirts, them Rock WWE Versace joints, saw white people in all of that. We as black people probably make up less than 10% of high end fashion revenue. Not to mention there are plenty of high end brands we've never even heard of, you just have to be in the know. But hands down white people are the primary consumers of that stuff, not sure what gave OP the idea of anything other than that.
Also, most super rich people consider off the rack clothes as rags
basically Polo compared to Gucci is what Gucci off the rack stuff is compared to whatever it is they wear.