I guess it’s the people that usually buy from this brand and like Green Day. It’s expensive shit, but that’s kinda normal for a fancy fashion brand. I don’t know nothing about fashion, but seems like this is not some random name but a quite established house selling a lot and doing some interesting stuff: https://www.voguebusiness.com/companies/subcultures-and-cinema-why-brain-dead-isnt-just-about-the-clothes
Whether it’s ethical or not to sell a t-shirt for 50$ I can’t say. If enough profit goes to the creatives that designed it, and the production line has some good ethical standards in terms of worker rights, material sourcing, etc. that’s unfortunately a reasonable and normal price.
What is for sure unethical is all the 5$ clothing which is sold at that price thanks to labour and environmental exploitation. And what is unethical is people getting paid shit wages so that they can only afford shit clothing.
But it’s all good, let’s enjoy capitalism.