Interesting question and here is the best ELI5 I could do.
The reason why electrons (charges) don’t fall down or bundle up at the bottom is the same reason why dust seems to float. Dust is very light. The force gravity exerts on an object is proportional to its mass. This means that dust particles experience very little downward force from gravity. So little in fact, that small air currents and buoyancy are enough to overcome gravity. Electrons are increadibly light compared to dust, therefore the force they experience due to gravity is miniscule compared to every other force acting on them. This is the case for free floating electrons (ions) as well as bound electrons. Usually electrons don’t like being on their own, and whatever caused them to split away from their nucleus had no trouble overcoming the weak force of gravity.
If electrons are bound in an orbiting around a nucleus the forces that keep them in orbit are also way stronger than gravity. While gravity acts on the nucleus as a whole, electrons will not split from them on their own.

To get a little bit more complex, “electricity” isn’t a singular thing, its just a broad term for charges and how they behave in electric and magnetic fields. Gravity is also a field. What makes electrons move is the direction of all those fields and their strength. We can’t manipulate gravity fields, but by applying voltage that we created using magnetic fields, we can manipulate electric fields. In other words we can tell electrons how to align or where to go. And even very low voltage is enough to overcome gravity.