The biggest fear in investing is stepping out of your comfort zone.

Warren Buffett once said, "I only invest in businesses I understand." This statement alone cuts down 90% of potential investments.

He also frankly shared his view on Bill Gates: "Gates is the smartest businessman I've ever met, but I really can't see what Microsoft will look like ten years from now." Yet, he added, "Chewing gum will still be chewing gum ten years from now. The internet can't change people's habit of chewing gum."

This is the true essence of the circle of competence.

The size of your circle doesn't really matter. What's important is that you stay within it. Opportunities outside your circle may be tempting, but don't be swayed. Focus on doing what you understand well—it's better than anything else.