The increase in Banksy's cultural cachet means that his next pieces sold at auction will likely be valued much higher than they would have been if this had not been in all the papers.

I can't say it's not a brilliant piece of art. It's quite similar to Duchamp's ready-mades[1] in that it's a critique of art itself.

https://en.wikipedia.org/wiki/Fountain_(Duchamp)[1]

Hia other stuff will sell for more because his name is better known? There is almost always profit to be made from being in the news.

That might be the profit in and of itself.

I bet Thomas Pynchon isn't just in it for the money. He probably likes the idea of people enjoying his books, too.

It's called PR

He bought it by proxy.