Once in a lifetime? I am 30, so far the currency, commodities and stock market have had at so many crashes of which I know of (Dotcom, 9/11, Lehmann, Greek/Euro crisis, Corona, Abenomics, Iraq war, Brexit) The magnitude does differ, but there is on average every few years one.
%% YES,DCC; print out a 10 year monthly paper chart of QQQ, or SPY or XLK/buy one share. That will show you how to trade/invest.May want to use 3 year weekly charts also- I do. Most anything works in an uptrending bull market/above 200 day moving average. DO NOT trade/invest with money you cant afford to lose IF not in usa/find etfs like those.Wisdom is profitable to direct...………………………………………...
Most of those are small events. Only Lehmann (aka Global Financial Crisis) and Covid-19 really count here. If you are 30 you probably weren't old enough to trade through Lehmann. So there has been only one once-in-a-lifetime vol event in your adult or "trading" life (career) so far.