As he said in his writing he simply assumed that whoever he is dealing with would give him what is fair. So he accepted the $20K and he was probably perfectly happy with his cucumber. Then later after a bunch of extra money is funneled into the company he sees a bunch of other people getting grapes for what he perceives as a similar effort to his own. Now the deal stops being fair in our monkey brains and we are hard-wired to demand equivalent payment.

However business economics has an entirely different concept of what is fair. It assumes everything is fair as long as promises are kept and deals are honored. There is no concept in business of renegotiating compensation of old contracts if someone else gets more compensation for a similar effort. This is why collective bargaining by unions is the only way for everyone to get equal pay for equal work.

> He asked for their offer, Mojang offered $20k, and he took the money.

The way I'm reading it is that he didn't even want to talk about the money. It had to be all about the art. And yet he clearly has lots of feelings about the money. Like I said, it's mostly his own attitude that's his problem. And although he claims lots of personal growth because of this, I'm still not sure he really understands that he's mostly projecting his own issues on others.

Still, he's probably right that he still owns it and Mojang only had a license, and giving it to the public domain is a nice gesture, if made with some grandstanding.