Never underestimate the determination of a kid who is time rich and cash poor.
there was no greater natural advantage in life than having an enemy overestimate your faults, unless it was to have a friend underestimate your virtues.
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
Technically, I am unarmed. But no one should ever underestimate the harm that fingernails can do. Especially if the target is unprepared.
Undeserved praise causes more pangs of conscience later than undeserved blame, but probably only for this reason, that our power of judgment are more completely exposed by being over praised than by being unjustly underestimated.
Never underestimate the power of stupid people in large groups.
There is no such thing as an underestimate of average intelligence.
Too often we underestimate the power of a touch, a smile, a kind word, a listening ear, an honest compliment, or the smallest act of caring, all of which have the potential to turn a life around.