I'm going to add that I did a rudimentary an analysis of the S&P 500 because everyone seems to be throwing their money into passive S&P500 low vehicle investments. I looked at every hold period since inception from 1 year holds / returns up to 40 year hold and returns. Timing is crucial for good returns - depending on when you put in and take out your money the returns can be negative (even in cases where you hold up…
To me the takeaway isn't that "timing is critical for good returns" but that "you can't time good returns, so don't move all your money at once". You'll be investing over the years of your career and withdrawing over years of your retirement. Historically, it ends up working out.