To the first part - I may not be able to change anything by not spending money on an asshole artist, that's true.

I may not be able to stop a corrupt politician from getting elected by voting for their opponent. Isn't it still worth it to cast my vote?

For the rest - I guess I think about it this way - an artist's art is an extension of their humanity, and what they think it means to be human. It is in many ways how they view the world.

So a) I find it hard to believe that their views don't make it into their work either overtly or covertly, and b) by commercially supporting these people I am endorsing their views. Now (b) might be a stretch for people, and I'm not saying that everyone must do this, but it is an ethical standard that costs me relatively little (oh no I don't get to consume to whatever vehicle the HP universe is putting out this month) and gives me a benefit (I feel good about keeping my money spent on people I feel worthy of my support).

There's so much art out there ready to consume, and so many artists to support. I can be picky and still have a rich and full life.