Here is a question, why dose the saver get interest for a loan when it is loaned just to another consumer. The borrower simply performs the consumption of goods that the lender has deferred, their is no overall reduction of consumption, yet the lender still takes interest.
Continuing to take on debt for non-investment consumption is not sustainable and probably not a smart loan to have made in the first place. This is what happens when you have unethical short-term bonus-seeking behavior on the part of bankers with unlimited printed money to play with.
The capital ideally goes towards productive investments. Unfortunately, since the banking system can print money to buy any "investment" (like no-Doc home loans in Detroit) they can find, that leads to loss of investment discipline, malinvestment, and economic contraction as the bad investments are written off. This is exactly what we are going through right now and it is going to get much worse in my opinion. The responses of the Keynesians to their obvious failure is basically, "Well, it's because we aren't making enough bad investments".
I think what you are missing is that savings that would otherwise go to pointless consumption does not bid away the goods and services that productive investments could use. That's a good thing.