Only chasing trends, avoiding consolidation—all hindsight. The market grinds 80% of the time, so "no signal, stay put" makes you miss small gains; "strong signal, go all-in" is just catching falling knives. Take profits at 15% by reducing half? Most of the time you never even get there—you're underwater the moment you enter.

Third, rule-based discipline supposedly controls emotion, but really it controls your wallet.
3% stop loss per trade? Frequent stops mean continuous losses.
Take 5% profit then cut position size? Just when things look good, you're pressured to lock in gains and miss the big money.
Don't add on dips? Yet you'll be tempted to "bottom fish" or "average down," losing more with each add.