This is a classic red herring thrown out in this argument. "We should be spending this money on schools, not stadiums!" Unfortunately it doesn't work that way. There IS NO POOL OF MONEY out there waiting to be spent. The money doesn't exist yet. The money to pay for the stadium would be generated during, and after the stadiums construction from increased tax revenue, liscencing fees, etc...
This model works in other cities, it can work in DC. But this nonsense about how DC should spend its money differently is just that.... nonsense. Good, so MLB is going to leave, and the Anacostia waterfront can remain a crime-ridden hell hole just as it is now. Filled with strip joints and check cashing stores.
Congrats DC, you're about to get exactly what you wanted! A populace dependant on the city council for its wellbeing.