Whenever Dow puts on a large gain, you start buying into the market the next morning at first bell to catch a trade except that it opens 5-8% higher for many small stocks, and maybe you could gain 2-4% intraday which is not enticing enough to sell for a quick gain. So you hold for another day, only to find that the very stock you bought retrace back again the following day, some by half of the previous day's gain, others possibly erasing the entirety of the gains the day you bought them. Then you're caught/stuck and become hopeful the turn in Wall St can sustain. You're up 2-4% only to have the week after erasing 10% so you are now losing money. It is a difficult way to make money, especially when markets are still more likely to tank lower ahead. That is what trading can look like playing bear rallies.
But if you bought once the coast is clear, and you start seeing markets sustain their upside for longer than a week on a higher high higher low basis, there is greater confidence and validation that the lows may already be in. Coupled this with some large positive catalyst e.g Powell declaring a Fed pivot, a Ukraine ceasefire or a large Chinese economy rebound, and bang the confidence is well grounded and justified.
Which is why I prefer to buy higher once validation and let bottom pickers buy their lows thinking they're lower enough.
