We're giving him lots and lots of cash to allow him to do a huge print run that he would otherwise not be able to do and would in turn make him more money and spread his work to people who might not know about him. In return we get awesome stuff. It's called mutualism. It is a form of symbiosis.
We're like bees spreading his pollen around to help the flowers grow and spread, and in turn we get nectar for our honey... or would it be the other way around?