I beg to differ:
"Think about it.
The input pin represents a 100 Mohm resistor to ground.
The pullup /pulldown resistor is out of the circuit UNLESS the button is pressed.
This means the pullup/pulldown resistors are not conducting any current unless you press the button.
"
The input pin represents a 100 Mohm resistance, not necessarily to ground, but to input signals. If this ls left floating, there can be triggers above and below the threshold to represent a high, and a low signal.
The pullup/pull down resistor is only out of the circuit when the button is pressed.
The pullup/pulldown resistors are providing the voltage level only while the button is not pressed. Then the button overrides them once pressed.
As I see it.