The common advice to 'buy more cheaper' when a stock falls is a flawed strategy. It often leads to allocating more capital to your worst ideas and compounding mistakes. Instead of automatically adding to losers, the bar for re-investment should be exceptionally high.

To combat the emotional burden of binary sell-or-hold decisions, use the "Go Havsies" method. Instead of selling a full position, sell half. This simple algorithm diversifies potential outcomes—you benefit if it rises and are protected if it falls—which significantly reduces the psychological pain of regret from making the "wrong" choice.

A powerful risk management technique is setting a maximum percentage of your portfolio that can be invested in a single stock *at cost*. A 5% at-cost limit means once you've invested 5% of your capital, you cannot add more, even if the stock price plummets and its market value shrinks. This prevents chasing losers.

The goal of diversification is to hold assets that behave differently. By design, some part of your portfolio will likely be underperforming at all times. Accepting this discomfort is a key feature of a well-constructed portfolio, not a bug to be fixed.

Contrary to the "buy the dip" mentality, David Gardner's strategy involves adding to positions that have already appreciated. This "add up, don't double down" approach concentrates capital in proven performers and prevents throwing good money after bad, which he identifies as the primary way investors go broke.

The sign of a working diversification strategy is having something in your portfolio that you're unhappy with. Chasing winners by selling the laggard is a common mistake that leads to buying high and selling low. The discomfort of holding an underperformer is proof the strategy is functioning as intended, not that it's failing.

A small losing position can occupy a large portion of your mental bandwidth. Selling a stock that is 1% of your portfolio but 10% of your mental energy is often a smart decision, freeing you to focus on better opportunities.

Since 2020, even top-quartile stock pickers have faced extreme drawdowns with concentrated portfolios. A more diversified approach, holding more names than usual (e.g., 50-75 stocks for an institutional manager), has proven superior for mitigating risk and achieving better performance.

Unless you are a full-time, proven professional trader, you cannot possibly know enough to time the market or predict specific outcomes accurately. The only rational strategy to protect against this inherent ignorance is diversification across various asset classes, rather than making concentrated bets.