Rabbi Haninah knew that to stick his foot into the lair of a poisonous snake was the right thing to do at that time. His wisdom enabled him to choose the right course of action that would serve as a moral for centuries to come. Wisdom enables one to perceive right courses of thought, of feeling and of action. Feelings become like tidal waves along the seashore, always causing havoc. Without wisdom, one's actions are erratic always hurting oneself and others.
Wisdom therefore is the monitor and the guiding light of the soul.
As important and crucial as wisdom is to human success, it cannot sustain itself unless two other elements are present. Mind you, Rabbi Haninah's words are not telling us how to initially acquire wisdom. He is speaking to those who already have acquired it. Rabbi Haninah is giving a warning to those already on a high spiritual level, how they must maintain themselves, lest they fall from their lofty heights. If the highest of angles can fall, then so can the highest of men.