Why $700 billion?

Once again, the Daily Kos is delving deeper into the bailout "crisis" than anyone else I've seen. Here's a sample:

The $700 billion figure isn't an explainable one, given the purported problem at hand of "bad mortgages".

And that's where we get that math problem. 1% of all mortgages -- the amount now in default -- comes out to $111 billion. Triple that, and you've got $333 billion. Let's round that up to $350 billion. So even if we reach the point where three percent of all mortgages are in foreclosure, the total dollars to flat out buy all those mortgages would be half of what the Bush-Paulson-McCain plan calls for.

Then we need to factor in that a purchased mortgage isn't worth zero. After all, these documents come with property attached. Even with home prices falling and some of the homes lying around unsold, it's safe to assume that some portion of these values could be recovered. In the S&L crisis, about 70% of asset value was recovered, but let's say we don't do that well. Let's say we hit 50%. Then the real outlay for taxpayers would be around $175 billion.

Which, frankly, is a number that Wall Street should be able to handle without our help. After all, the top firms on Wall Steet payed out $120 billion in bonuses alone between 2000 and 2006. If they've got that kind of mad money, why do they need us to step in now? And why do they need twice as much as all the mortgages that are even likely to implode?