Sports teams often threaten to leave the cities where they play, if they don't get nice new stadiums paid for by taxpayers. (Imagine if, say, Wal-Mart tried that for one of its stores.) The funny thing is, sports franchises don't like to directly answer "Would this be a sensible investment for the city?" If the answer is yes, there's a case to be made. If the answer is no, then you would expect the teams don't want this talked about out in the open, and then they rely on sports tribalism and mostly indirectly threaten the local mayors. That is, many voters are economically irrational and care about their team even if it's costing them money, and will vote out the mayor if he lets the team leave on his watch. This has already happened at least once. And (surprise!) the answer is a clear no, where new stadiums are concerned - they don't bring growth to the area around the stadium, or money into the region. (That's a Stanford study at that link. What, you don't believe Stanford, the engine of Silicon Valley? What are you, some kind of a communist?)
But other cities have told teams to get lost, and done just fine afterward. Here's another such story in Phoenix. And while we're at it, ask yourself: has San Francisco been hurt economically after telling the 49ers not to let the door hit them in the ass on the way down to Santa Clara?