Current doesn’t flow to the ground; it flows through the ground and back up. If there is electricity moving into the ground from an energized conductor, go back to the source of that conductor and see what’s happening. For the grid, it’s probably a transformer or electrical generator, in either case, a simple coil of wire. And, the electrical current flowing out of the coil has to be equal to the electrical current flowing into it, whether that current is coming from one of the other phases, a neutral line, or an electrode buried in the ground.