1) Pride. They wanna be one
AND
2) Fights. They want to point farm
I know a lot of big headed people who wouldn't be able to stand not being ranked well. So they'd spend diamonds to feed their egos.
you ain't wrong about the egos. but I said no one "in their right mind", i.e. no rational player who's in-game actions are to benefit their city, and maximise resource use etc.
I'm also not sure if the battle points gained in this AivAi arena are counted towards global ranking?
and if they are, players get in plenty of fights in GBG, neighborhoods, RQs for SAAB, etc. even the most avid point farmers won't spend 50 dias just to get another fight...