Rowling spends almost every bit of income she gets on funding anti-transgender organisations and literal fascists (such as Posie Parker), whose lobbying efforts have turned every major British party against transgender healthcare, resulting in transgender healthcare becoming practically inaccessible through legal means with waiting lists lasting decades.

In terms of its material impact, buying HP merch is equivalent to buying a swastika flag from a neonazi store. You can be assured that every cent of profit will go to funding fascism. The only difference is the aesthetic of having HP merch versus having nazi merch.