Sports also bring joy to people, which costs money. I'd rather have governments spend money on sports than on a whole lot of other things.
Obviously it would've made a lot more sense to have built 1 multiple purpose stadium, but from what i've read your American football team is at fault there.
11 years ago my team got a new stadium and there was a lot of protest because my town had to pay around 10 million for it. Since then we promoted to the top flight, won the cup and the Johan Cruijff trophy. The number of supporters has gone up 3 or 4 times, our small town now has nationwide recognition and small businesses in the town make a whole lot of money on matchdays.
You hardly ever hear anyone about the costs of the stadium anymore.