Right, risk plays into it, but the loan the bank creates is an asset, (a liability for the bloke that has to pay it back in the future) - If I can sell that loan to someone else great, I just have to make it look low risk. But whether or not I sell the contract/loan off, I do have an asset that I didn't have before. It may not be a dollar from the Fed, but it's worth a dollar as long as the risk is low.