It's not that simple. The word "assets" is the wrong word (and I know, you didn't pick it). What actually happened was that there were two kinds of assets, safe and... not so safe. And when the bottom fell out on housing, people got out of the stock market too. Where did the money go? Some evaporated, as people found out that their assets weren't worth as much as they thought they were. A bunch of the rest went into bonds, especially US Treasuries, which were regarded as the safest asset out there.
The Fed responded by buying a bunch of treasuries (QE). That drove the price up. If you happened to hold treasuries when the Fed did this, you made money. On the other hand, everyone else on the planet was also buying treasuries, so the price was going up anyway - the Fed just made it go up more.
So some people sold, because the price was high. Some did it to cash in the price rise. Others did it because, going forward, the rate of return was dismal for the next X years. Those who sold had to put their money somewhere. Where would they put it. Not in treasuries - that was what they were selling. So they were getting out of treasuries, and had money to buy other things. That's what the Fed intended.
But it's not just QE. It has always been a good strategy to hold bonds when interest rates fall, because the price of the bond moves in the opposite direction of interest rates, and the longer the bond duration, the further the price moves.
Why did the Fed do this? A few paragraphs ago, I said that some money just evaporated. Well, "some" here means four trillion dollars. So the Fed used QE to create four trillion dollars and pump it back into the economy, which kept the whole thing from seizing up in a real Great Depression. Whether people holding treasuries at the time made a bit more money than they would have is beside the point.
So freejulian is wrong in what he's implying, that there was some conspiracy of evil bankers to transfer money to the rich. But he's right that, when this came down, holding bonds was the right move. (But by the time QE started, the big gains had already happened.)