[sidr]

> just how important big teams like say, Chelsea or Barca are for a huge chunk of not just the people who live in their home cities but also across the world.

Here "important to" is equivalent to "liked/entertained by", as a form of entertainment. The question here is what forms of entertainment should tax payers pay for and your comparison with art museums, operas and orchestras is apt.

> let's say barca wanted to leave Barcelona, do you think the city shouldn't do anything about it because it helps billionaires?

If barca were extorting the city of Barcelona by demanding they pay 10s or 100s of millions to upgrade Camp Nou, then the city should tell the team to go to hell. This exact scenario has played out in multiple cities in the US and with the IOC and city bids.