That's just how it was packaged, for Night's benefit. This goes to his company, as does a further $300K for his services as "writer", and a further $2.5 million for his services as "producer". Oddly, his pay as "first unit director" is said to be "scale", amounting to just over $200K. So his total pay package was around $10.2M for writing, producing and directing.
Also, marketing costs don't appear in this budget, that's a separate expense by the studio. Hence all that talk about how a movie might have a $100M budget, but "after marketing it'll be doubled".
What's interesting is that the first billed cast member, Bryce Dallas Howard, only got $150K, Joaquin Phoenix got $5M, Adrien Brody $3M, Sigourney Weaver $2.25M and William Hurt "just" $1.25M, less than Brendan Gleesen's $1.5M. Whilst explicable because Howard was a newcomer, it's still a huge difference. I'm also slightly surprised at how low Weaver's fee was, but then again this isn't an Alien movie (where she could demand whatever she wants). Also surprised that Hurt was the lowest-paid of the stars, considering his pedigree, but I guess he's not much of a box-office draw.