From the always amazing Berkshire Hathaway annual letter to shareholders (2009), by Warren Buffett:
"Charlie and I avoid businesses whose futures we can’t evaluate, no matter how exciting their products may be. In the past, it required no brilliance for people to foresee the fabulous growth that awaited such industries as autos (in 1910), aircraft (in 1930) and television sets (in 1950). But the future then also included competitive dynamics that would decimate almost all of the companies entering those industries. Even the survivors tended to come away bleeding.
Just because Charlie and I can clearly see dramatic growth ahead for an industry does not mean we can judge what its profit margins and returns on capital will be as a host of competitors battle for supremacy. At Berkshire we will stick with businesses whose profit picture for decades to come seems reasonably predictable. Even then, we will make plenty of mistakes."
WARREN BUFFETT
Berkshire Hathaway's 2009 Annual Report to shareholders
PS: Another great quote showing how honest Buffett is:
"GEICO’s growth may slow in 2010. U.S. vehicle registrations are actually down because of slumping auto sales. Moreover, high unemployment is causing a growing number of drivers to go uninsured. (That’s illegal almost everywhere, but if you’ve lost your job and still want to drive . . .) Our “low-cost producer” status, however, is sure to give us significant gains in the future. In 1995, GEICO was the country’s sixth largest auto insurer; now we are number three. The company’s float has grown from $2.7 billion to $9.6 billion. Equally important, GEICO has operated at an underwriting profit in 13 of the 14 years Berkshire has owned it.
I became excited about GEICO in January 1951, when I first visited the company as a 20-year-old student. Thanks to Tony, I’m even more excited today."