gold, page-44224

booms were manias, every man and his dog were into it

Tulips, stocks, property. Booms and bubbles all share the same characteristics.

whereas it can be clearly demonstrated that buying stocks in any serious downturn can be extraordinarily profitable.

Righto, so this is 'buy low, sell high'.
Stocks decline, buy low, sell high later. Extraordinary profit.
PM's decline, buy low, sell high later. Extraordinary profit.
Property declines, buy low, sell high later. Extraordinary profit.