You can't judge the quality of decisions you made in the past based on what you know now. Imagine going to a casino, putting $100 on red in the roulette wheel, black coming up and then thinking, "Man, I really regret putting it on red, I should have put it on black".

How is that in any way useful or going to improve future decisions? Bet on black, because you know, that's where the trend line is going?

Case in point: Do you short Bitcoin now or not? Who freaking knows...