40 with no kids and you have an entertainment budget....Typical 1991-2013 Weekend: Saturday: drive to FP, have a beer, watch the game, drive home. Sunday: Catch up for breakfast with a friends on Semaphore Rd, lunch with the GF and arvo movie on the Parade and/or drinks somewhere.
Typical 2014 Weekend: Saturday: drive to Nth Adel with GF, pre-game lunch/drinks with others I go with, walk to the ground, have a beer, watch the game, more beers, wait for the GF to pick me up, head into town, dinner out, movie and/or drinks somewhere. Sunday: veg at home.
Am helping the City traders out (who have done nothing but bitch up lack of trade for the last 20 years)? Yes. Am I spending any more money? No, because I have a weekly amount I budget for entertainment and when it's gone it's gone. So do the suburban traders now get a bit short changed because I am not spending it there? Yes.
Gain to the economy = $0
And I am 40 with no kids, no rent or mortgage to pay. So I can only imagine (and know for a fact) that family unit's are pretty much doing the same thing, are they consolidating their days around CBD footy, absolutely, you have the museum, the zoo, any number of things that you can do in the city prior to and sometimes after some games but not too many of them are backing it up the next day at Marion taking the tribe to the movies and the like, people don't live beyond their means just because we have a great CBD stadium.
The only boost is from interstaters spending their money here, not locals.