…and one can move the Earth.”
Theoretically, of course.
Practically, the fulcrum would have to be strong enough to support the enormous load. Realistically, the lever would have to be able to balance the Earth on it, while the fulcrum is sitting on a much larger planet, and the force is applied from a 3rd planet.
This saying is meant to only illustrate the power of understanding physics, but like anything, the understanding can be taken out of context, and provide those who don’t fully grasp the concept to think more is possible than reality.
If you can understand the details of what this implementation would actually look like, requiring 3 planets, then you understand the limitations. Apply that same notion to any simple saying to test understanding.