Source

Even Warren Buffet Makes Mistakes
Quote: “You’d have been better off if I had gone to the movies [this year]” and: “I have erred [by] not making repurchases [of shares].” In 2004, when asked at the Berkshire Hathaway annual meeting what his worst investing mistake was, he explained: “I set out to buy $100 million shares of Wal-Mart at a [pre-split price of] $23. … We bought a little and it moved up a little and I thought maybe it will come back a bit. That thumb sucking has cost us in the current area of $10 billion.”"

At least he admits to making mistakes, it is much easier to talk about only the winning bets and silently forgetting about the mistakes.