If the top is completely vertical, the ground is smooth, and there is no resistance and external force, it will not shake. In daily life, because the gyro is not vertical, the component of gravity in one direction will produce a moment with the top of the gyro as the rotation point, which will reduce the rotation speed (angular velocity) and change the direction of angular velocity. Because the angular momentum is getting smaller and smaller, the tilt angle of the gyro will become larger and larger, and finally the gyro will lie flat on the ground and roll. At this time, the moment of gravity is zero for the whole gyro. If you pull a whip in the direction opposite to the gravitational torque, the gyro will continue to turn. So some people smoke well, and some people smoke badly.