Why do all big planets have rings and small planets don't?

Small planets don't have rings because they are land planets and are made out of rocks. Smaller land planets are Mercury, Venus, Earth, Mars, and dwarf planet, Pluto , Eris. Bigger planets have rings due to their gas. Bigger plants like Jupiter, Saturn, Uranus, and Neptune are made out of different gas particles. You can never land in these planets. So this is the reason why bigger planets have rings.