Understanding pull down resistor current flow
No current flows in or out of the input pin.
It has no path for current to flow, whether the input pin is connected to 5V or 0V (ground).
So no current flows when resistor keeps the voltage at 0V.
When DIP is set ON, only current from 5V flows via resistor to ground.
That is how ideal input pins work. In real life there could be some leakage currents flowing in the order 1 microamps, which for simple beginner circuits can be ignored.