Why a are gas giants larger than earth?

Gas giants are larger than Earth primarily due to their composition and formation process. They are primarily made up of light gases like hydrogen and helium, which allows them to accumulate a massive amount of material without a solid surface. Additionally, their formation in the outer regions of the solar system, where there was more available gas and ice, enabled them to grow larger as they attracted and retained these lighter elements. This results in their significantly greater size and volume compared to terrestrial planets like Earth.