Should Taxpayers ever fund large stadia/arenas?

[Since I'm the mad scientist proclaimed by myself]

As I recall, I get a +2 happiness per stadium in Civ V, so seems like a good move.

even if that transferred to real life, it still wouldn't be worth it (and it wouldn't be worth it in game if it only gives you a couple of happiness....though I suppose I haven't played Civ 5 much in years and don't really remember how hard it was to keep people happy....wait...didn't that one have that weird civ wide happiness deal and not per city like all the other Civ games? ugggg, bad game  Civ 4 with mods is still the best Civ experience)

Yup, Civ V has civilization-wide happiness. It's what I've played most, so I don't really know any other system. But point being, if happiness gets too low, rebels pop up and productivity stalls, so, yes, happiness is important. Re Civ IV: Might have to pick it up at some point.

Civ 4 is great, its simultaneously much deeper and more fast paced than V.