So much of the data of economic benefits are nebulous to say the least. Hosting the biggest sporting event in the world will undoubtedly bring in a massive amount of money.
You are right to say though that infrastructure for such an event requires a certain level. Now, this can be a good thing if those improvements see use for years to come, such as upgraded road and rail.
There is also the argument that these events are a showcase for the world as massive tourism advertisement. How true that is? Hard to say and likely won't know for Brasil until 2020 or so how this all plays out.
I am a bit surprised in a football mad nation there would be this resistance. It will be 64 years since Brasil lost to Uruguay at the last World Cup there and always imagined Brasilians wanted it back pretty much ever since.
