Oh for the good old days of a nice, clean housing bubble and bust as in 2004-2011: subprime lending expanded the pool of buyers, liar loans and loose credit created speculative leverage, the Federal Reserve provided excessive liquidity and the watchdogs of the industry were either induced (ahem) to look away or dozed off in a haze of gross incompetence.

The bubble burst was also straightforward: unsustainable debt, leverage, fraud and speculation all unwound in 2009-2011. The cause was obvious and the effect easily predictable.

Alas, today's housing bubble and bust has these curveballs:

1. A stupid amount of cash sloshing around the world.

2. Who has the cash and an interest in using it to buy houses.

I considered the two conventional explanations for the current bubble in Is Housing a Bubble That's About to Crash?: 1) a housing shortage and 2) the Federal Reserve buying mortgage-backed securities and flooding the economy with cheap credit, causing mortgage rates to plummet to record lows.