There is a concept of saturation in Helium network. You can see the effect in real time as rewards are plummeting in oversubscribed areas like San Francisco. To

There is a concept of saturation in Helium network. You can see the effect in real time as rewards are plummeting in oversubscribed areas like San Francisco. Too many nodes --> reward scale goes down --> network deployments percolate towards the perimeter where ROI is better --> Network grows in geographic coverage. This is the beauty of the proof of coverage scheme. Its an awesome way to distribute rewards to people who provide valuable coverage while simultaneously creating a force to disperse over a large geographic area.