Don't wish to get into a battle of economics, this is not the place.
However the point in your statement is National "wealth".
Wealth is not the same as cash. Much of that loss was in assets on paper(such as shares) or some such as real estate (commercial and residential), which many on both sides realised was in some cases very over valued.
If someone steals $500,000 out of a safe in your home, you have lost real money. If your home goes down in value by $50,000, you have lost nothing tangible, except what someone might have been willing to pay for your home. There was never any promise you would have gotten that amount. Maybe you would, maybe you would get less or more, but there was no way of telling.
What Amercians are going through now is a major readustment to their wealth. No longer able to use the perceived value of their homes as a piggy bank, nor able to continue running up debt based upon fantasy figures of future potential income.
If one looks at who benefitted the most from this last bubble, it is not just the "fat cats" everyone wishes to lynch. But our parents, and other elderly who did what they were taught by the lessions of the Great Depression; they worked hard, saved, purchased homes and stayed put for the most part, the market did the rest. Someone who paid $25,000 for their home in 1965, probably could have sold it up until recently for several hundred thousands. Combined with savings, a pension and the lot, these persons were sitting pretty (until the recent market upheavals).
The Baby Boom generation and those that are following are going to have a very hard time keeping up with their parents standard of living, much less passing it. This is not just a Republican or Democrat thing either, for decisions made when either party were in power are responsible. Problem is now all those chits are coming due and there is no money in the kitty. Obama and the Democrats are making all sorts of proposals, but not saying how or where the money is going to come from. On the other side, the Republicans probably aren't offering much assistance either. What is clear is taxes are going to have to rise sooner or later, and not just on the "rich", either.
What one must remember about wealth and the wealthy these days, is that it is portable. Tax certian persons to death, and they will leave one area of the country for another, if not the entire country all together. Ever wonder why so many UK residents, especially the rich and or famous end up on these shores? Well it has much to do with the fact the taxes in the United States are vastly lower than in Britian. Same reason Russians worth billions flee that country and live in Britian.