I've heard the gold theory a lot, but my current best theory is it wasn't until credit cards became ubiquitous that wages stagnated and the debt treadmill began. There was also a significant population increase in the latter half of the century, there - but forget looking at milk prices or gasoline prices - look at a ford mustang, or a motorhome - or even housing.

Once a certain segment of the population realized that real estate was "undervalued" relative to the potential for collecting rent on the undervalued property - yeah. rent goes up, wages don't at the same rate, more credit card debt. High debt means you're paying nearly all interest, so that ain't going down.

Oh and does anyone actually remember earning a decent amount of interest at a bank? man, those were the days. 12 month 7% CDs, lol.