Lighting rods also work by dissipating the local electric potential and reducing the likelihood of a lightning strike. That's why they are pointed, or fractal in the newer ones.

From https://en.wikipedia.org/wiki/Lightning_rod "and that a considerable electric current can be measured through the conductors as ionization occurs at the point when an electric field is present, such as happens when thunderclouds are overhead."

You can get a ground charge even when thunderclouds aren't present. It just has to be windy. I've always wondered if it was worth collecting this, say with a field with a grid of interconnected lightning rods in a windy location.