In November 2008, ABC News warned US taxpayers that government support for the country's financial sector would cost up to $7.5 trillion. It cited figures from macroeconomic analysis firm Bianco Research showing that, in 2008 dollars, the cost of the bailout would be more than the combined costs of the Marshall Plan, the Louisiana Purchase, the Korean War, the Vietnam War and the entire historical budget of NASA, including the moon landing.
The Treasury now expects TARP to cost the taxpayer nothing, yes, nothing. It expects TARP to make a profit. (Not like the Fan/Fred and UAW bailouts.)
The US government did not give Wall Street $800B. The government lent Wall Street about $300B, which it will get back, in full, with interest plus profits on the warrants for which it paid nothing.