Not sure I have an 'answer' but think it has something to do with the demand for money today vs the demand for money tomorrow.
Lots of the world's money is being held in the hands of those with...a lot of money.
Those people tend not to need money to spend it, and are looking for places to park it. Meaning there is a large supply of money today.
Meanwhile, lots of people need money, but there are fewer and fewer places where money can go and get a 10%+ return, so the demand for money today isn't that hot.
If supply is up, and demand is down, the price goes...down.
The 'price' of money today vs money tomorrow is basically the interest rate. So lots of supply, not much demand, and the price has collapsed.
Now why demand and supply are in that position, that's another (harder) story, and one that I've yet to see a good synthesis of.