Properly channeled, intelligence is a boon and a great helpmate. Misused, intelligence is a curse and a tyrant. We can overcome the insolent might by making intelligent choices. The true friend shares wisdom. In many ways, we are our own worst enemy, because we fill our mind with all kinds of nonsense and then make-believe it is real.
Many people know too much for their own good.
It means they think they know a lot, and what they know is not of much use to them. Someone could have an encyclopedia of knowledge in his head but still posses no common sense. It is uncommon to find someone whose actions match his words. People don't say what they mean, they do what they mean. In other words, their actions reveal their true intentions.