I saw it in the 1970s. Tons of dollars went into gold and silver. Many of those dollars were from unreported income, from delis, auto body shops, in general small one owner businesses that deal with lots of cash, and are on their honor to report all the income. Cash under the mattress.
They plowed all their private funds into physical Gold and Silver, and suddenly, due to purposely high banker (gov’t) controlled interest rates, Gold dropped from $850 and Silver dropped from $52, and evaporated all that cash in one fell swoop.
The real estate and other asset busts prior to 2008, also all evaporated tons of dollars. Real estate is also often used by tax cheater to hide and launder cash. Very simple. They buy a cheap house, hire and pay contractors in cash, sell the house for double, and bingo, under ground cash is turned into a legitimate deposit in a bank.
Watch this bit coin thing suck in zillions of dollars, and suddenly, out of nowhere, it drops hard and fast, confiscating all that cash. All the evaporated funds over decades (plus imports) could be why the Fed has rates so low.
The “boom” cycles do tend to add “found money” like welfare to the system to over ride lost incomes from manufacturing businesses.