I think it's very interesting so many people in this comment thread are so quick to point out that 20k is a fair, or even good, price for writing the end poem, but don't engage with the fact that $1800000k might be an excessive amount for one person to earn for making a video game.
The multiples and orders of magnitude of difference in the payouts are what make the decisions that the various people make interesting and complicated. The author did what he needed to do to make you feel those orders of magnitude in difference.
Also it is very funny to think that somebody who has 1.8 billion dollars is not greedy. I don't think that is impugning their character to point out something obvious.