Warren Buffett"s memorable investment failure with Dexter highlights the importance of avoiding over-reliance on management and the need for a sustainable competitive advantage. The lesson is that while strong management is crucial, it"s more critical to invest in a good industry and company, not just a seemingly talented team. Buffett"s experience with Dexter serves as a reminder of the dangers of linear thinking and the pitfalls of investing in a company without a clear moat.