Why are bond yields so low?

There are myriad reasons why bond yields are so low. I have found it useful to list them so that I have a framework for seeing the various parts and gauging how they change over time. Here is why bond yields are so low:

(1) Relatively low inflation.
(2) Exceptionally low short term rates (controlled by the Fed).
(3) The investor fearful of deflation.
(4) The investor fearful of equities.
(5) The investor who is simply fearful.
(6) Foreign central bank buyer.
(7) Federal Reserve POMO monetization.
(8) The ride-the-yield curve financial institution buyer.
(9) The front-run the Fed speculative buyer.
(10) The momentum buyer.