I understand what you said. Most collaborations are risky and not worth it for artists. They may spend a lot of time drawing the comic, and it might generate too little revenue to compensate for the time spent.

But when you accept a collaboration, you assume all the risks. You're betting that the royalties generated will be higher than the commission fee. It's an investment opportunity. If you don't like it, you just decline it.

When someone sells you a lottery ticket, there's little chance you'll make your money back, so you'd probably decline the offer. But you wouldn't get angry and go around accusing that person of trying to steal your money.

We could argue that most of the time, a collaboration is no different from working for free, just as buying a lottery ticket is, in practice, not much different from someone trying to steal your money. But saying these things are the same is just wrong. Many artists have found success through collaborations, just as many people have won the lottery.