Why don't we fall off when the Earth is revolving at a high speed?

 

We don't fall off the Earth even though it's spinning at a high speed because of gravity, which pulls us toward the center of the Earth and keeps us grounded. The Earth's rotation creates a centrifugal force, but this force is much weaker than gravity. Additionally, we and everything else on Earth are moving along with its rotation, so we don't feel the movement. It's similar to how you don't feel like you're moving when you're in a car that's driving smoothly at a constant speed. The combination of gravity and the constant, smooth rotation of the Earth ensures that we stay firmly on the ground.