John C. Bogle
Biggest mistakes
Where the approach can fail and what to watch for.
Mistakes to avoid
No investing style is immune to mistakes. When studying John C. Bogle, look at the downside of the method: when it can be misused, when it needs special conditions, and what beginners often misunderstand.
Becoming overconfident after a few correct outcomes.
Using a method that does not fit your time horizon or temperament.
Ignoring capital management because the thesis feels strong.