Thing they don't get is gravity is not energy. It's not even a force. Gravity can generate motion and one can extract energy from it. But in general some effor

Thing they don't get is gravity is not energy. It's not even a force. Gravity can generate motion and one can extract energy from it. But in general some effort is required prior (like sun energy that fills up dams which later use gravity to generate hydroelectricity. Gravitational motion is not perpetual, either. Water flows towards the center of the massive object curving space-time and that's it. It won't flow in a cycle. Unless some other factor spends energy making it flow, i.e. the Sun. So a stationary generator that has no external energy input to keep motion flowing connected to gravity cannot generate energy.