Technically, the money comes from people who pay to use AI (customers), or alternatively to buy art from artists. To the extent they are out-competing artists,

Technically, the money comes from people who pay to use AI (customers), or alternatively to buy art from artists. To the extent they are out-competing artists, it's diverting a money flow from artists to somewhere else. But a lot of that money might be from people who would never have bought that art to begin with? In any case, the money never belonged to the artists. It never got to them. The people it actually belongs to (the customers) get to make the decision about what to buy.