Well completely putting aside people who want to be seen wearing a brand because they think it improves their perception or whatever - those people definitely exist but I’d say that’s an irrational behaviour that you won’t get a satisfying explanation for.

That aside, as it happens I’ve just had to buy a load of new sports gear recently and I’m new to the market so I don’t know what’s good. I want something that will perform well and last a long time, and I’m in a position that if I pay a bit extra then I’m not really going to notice. So, as in your example, I got some Nike stuff and some addidas stuff. My reasoning being that I see their brand as representing quality, and I presume that their stuff is going to perform well and last a long time. “buy it nice or buy it twice”. Sure I could buy some offbrand tat, but an offbrand is incentivised to lower the price, while Nike/etc is incentivised to get repeat, lifelong customers via brand loyalty

I say this, again, as someone unfamiliar with the market and these brands. But there’s my reasoning. I’m sure they’re not perfect brands and that they’re overpriced and that smart shoppers could get a comparable product for less. But I’m just some dude wandering into the sports shop and hoping not to buy a piece of tat that will last two uses and then fall apart, and I’m happy to spend a bit more for that piece of mind.