Risk comes from not knowing what you are doing so wide diversification is only required when investors are ignorant. You only have to do a very few things in your life so long as you don't do too many things wrong.
Warren BuffettYou really don't need leverage in this world much. If you're smart, you're going to make a lot of money without borrowing. I've never borrowed a significant amount of money in my life. Never. Never will. I've got no interest in it.
Warren BuffettOutstanding long-term results are produced primarily by avoiding dumb decisions, rather than by making brilliant ones.
Warren Buffett