150M isn't even close to covering a functioning public transit system in any major US city. Expansions of the subway in New York routinely run into the hundreds of millions of dollars, and that's just expansions. Even if you're looking at buses only, if you start with the assumption that each bus runs about $100k, that's a mere 1500 buses. The CTA in Chicago uses over 1800 buses--that only counts the ones currently in operation--so you're still short on building bus stops, bus lanes, any kind of light rail system, and so on. Oh, and lots of the bus lines in Chicago stop running after a certain time; I couldn't take the buses to go to any concerts, since nothing operated in my area between midnight and 5am.

Plus, you have ongoing operating expenses. Once a stadium is built, it's usually operated by someone other than the city.

I'm not saying I'm in favor of stadiums, but whoever costed this needs to consult with a civil engineer to come up with a more realistic figure for comprehensive public transit for major cities.