Contrary to popular belief, balance is not a vertical science of how things stack from the bottom up. Instead it's a science of how objects extend from their center out.
Planes, trains, and automobiles would not be able to functionally operate, without a principled understanding of center of gravity. Your body is no different.
If I asked you to stand on one leg, the panic of not having two feet on the ground will almost instantly spark some shaking in the legs, swinging of the arms, and rolling in the feet. Why? Because you are focused on trying not to hit the ground! Your physically manifested anxiety is layering on how your feet, ankles, knees, hips, and torso stack from the ground up.
The reality is that there are more forces at play, than just gravity pulling you downward. Instead of focusing on your body from the ground up, focus on your body from the center out. Your center being, your waist. That mysterious "lower dan tien" that exists just below the naval.
Next time you stand on one leg, don't see yourself as preventing gravity from pulling you toward the earth.... instead, see your core (waist) as pressing the earth down.
Balance comes from the center, not the bottom. When you discover the confidence that exists within your center of gravity...you will stop looking down.