[airair]

Gravity is earth pulling the club. Like a magnet pulling another magnet.

The higher you lift the clubhead in the back swing the more potential energy you create. Some of this potential energy will be transformed to swing speed as the clubhead drops towards the ground.

Let's assume that you lift the clubhead 2 meters above the ground in the back swing. And that your motion is so efficient that all the kinetic energy you've created by this lift transforms to swing speed. That will give you a mind blowing speed at impact of 14 MPH. If you stretch it and lift the clubhead 3 meters up you might get you up to 21 MPH.

My advice is to stick to TGM.

The way you explain it here - it seems like gravity is overrated with regards to the golf swing? Sure - I'll stick to TGM and their instructors.