[throwaway201103]

> nobody ever complains that cities subsidizing the construction of sports arenas

They certainly do. Many people object to this sort of thing, and say "if it's such a good idea, a private business should be willing to do it." Strangely they tend to not make this argument about things like public transport, even though it's exactly the same thing.

The arguement is that these arenas, convention centers, transit systems, etc. enable more economic activity and generate more tax revenue than they cost. I don't know if that's always (or ever) the case but that's the rationale and it's not insane.