See if this helps. Imagine a spherical, pressurized vessel filled with water, like a boiler. The water pressure exerts an equal amount of pressure on the inside of the sphere in all directions (ignore gravity.)
Now you drill a hole at one spot on the surface of the boiler. The pressurized water will shoot out of that hole. How does the water “know” to go through the hole? It doesn’t, but the walls of the boiler resist the water pressure, and the hole lets it through. The water will flow from the place of very high pressure to the place of low pressure. So when a water molecule happens by chance to go shooting off in the direction of that hole, it will go through, otherwise it will bounce off the inside wall of the boiler.
Another way for the water to get through, if there are no holes, is to build up greater and greater pressure until the vessel bursts at its weakest point (say along a seam.) Pressure wants to equalize itself and will do so when given the opportunity.
Now electricity doesn’t work exactly the same way, but “pressure” can be analogous to electrical potential in some ways. Think of the electrical charge building up between the ground and the clouds as pressure, and the atmosphere as the walls of the vessel. If the pressure becomes too large for the vessel to contain, the electrical current will flow from high pressure to low pressure. (The pressure, or potential, between two points is what we measure as voltage.)