The best macro traders (Jones, Druckenmiller, Soros) are defined by their ability to discard a viewpoint the moment facts change, rather than defending it out of ego. This intellectual flexibility is crucial for survival and success, as clinging to a wrong idea is a far greater error than admitting a mistake.

Successful investing requires strong conviction. However, investors must avoid becoming so emotionally attached to their thesis or a company that they ignore or misinterpret clear negative signals. The key is to remain objective and data-driven, even when you believe strongly in an investment.

Our brains are wired to find evidence that supports our existing beliefs. To counteract this dangerous bias in investing, actively search for dissenting opinions and information that challenge your thesis. A crucial question to ask is, 'What would need to happen for me to be wrong about this investment?'

Before committing capital, professional investors rigorously challenge their own assumptions. They actively ask, "If I'm wrong, why?" This process of stress-testing an idea helps avoid costly mistakes and strengthens the final thesis.

Absolute truths are rare in complex systems like markets. A more pragmatic approach is to find guiding principles—like "buy assets for less than they're worth"—that are generally effective over the long term, even if they underperform in specific periods. This framework balances conviction with flexibility.

Objectively track whether new information strengthens or weakens your belief in each holding on a monthly basis. This simple journaling practice forces a regular review, helping you decide whether to add capital or trim a position based on fundamentals, not share price movement.

To combat endowment effect and status quo bias, legendary trader Paul Tudor Jones advises viewing every position as if you were deciding to put it on today. This creates a zero-based mindset, forcing you to justify each holding's continued place in your portfolio.

John Bogle's wisdom holds that the optimal investment strategy isn't based on historical performance but on what deeply resonates with your core beliefs. This ensures you'll stick with it during inevitable downturns, preventing the performance-destroying behavior of return chasing.

McCullough advocates for a "promiscuous" investment strategy, quickly moving capital to where signals are strongest. He argues that emotional attachment to winning positions, or "bag holding," is the primary way investors lose ground. The goal is to compound returns by avoiding drawdowns, not by marrying a single investment thesis.