Why doesn't the gas planets just float away?

The gas giants Jupiter, Saturn, Uranus, and Neptune are all mainly composed of gas the only solid being the core which is rock, and metallic, The gas giants are all 95% or greater made of hydrogen which is a very light gas, what keeps all these giant gas planets together is that Jupiter is 318 times as massive as Earth Saturn is about 95 and Uranus and Neptune are about 20 times as massive as Earth, Meaning that the gravity pull of the gas giants is much greater than Earths and is what keeps all these gases together.

Comment: Yes. Also the fact that the planets are so far from the Sun helps stop

gas molecules etc., reaching "escape velocity".

A "hot Jupiter" would be losing matter, we think.