I think max money is based on a lot of factors...
Current production
Potential upside
Age (younger the better)
Then some more intangibles like player image (face of the franchise)...chemistry... value to the team.
I think Booker gets max or near max in almost every criteria. He's an extremely young scoring phenom with a good guy demeanor and a perfect image for a franchise. He can anchor this team for the next decade (contract willing).
I agree with that, what scares me though is McD and/or Sarver trying to offer him near the max to sign and he gets offended and decides to seek greener pastures. Without Booker this team falls back a decade, I don't care who they draft this year. He is the future of this club and considering he hasn't had any bad injuries or attitude issues, you pay him top dollar.