There are entire industries behind people like Rowling - book publishing, movie production, etc., subject to all the same exploitation of surplus value.

It’s similar to how we benefit from cheap manufacturing labor in other countries, performed by people we don’t know. Who did we underpay to get our luxurious lifestyles? The fact that we can’t name them is part of the sleight of hand that allows us to ignore the exploitation, but it doesn’t mean it doesn’t exist.

Sure. It's just not the norm. JK Rowling is essentially one of a kind. The tech sector is an outlier too, in that it is normal for founders to be significant technical contributors. In most of the economy, rich people become rich through rent seeking.

If the problem is people gaining through rent seeking, then attack rent seeking itself, rather than rich people in general.

There are poor people who make money through rent seeking too, by playing zero sum games. These zero summers should be targeted rather than the entrepreneurs, artists, writers, and musicians who play positive sum games.