Planets With Too Much Mass, and Too Much Atmosphere

Having too much mass can make it impossible for creatures like us to survive on a planet. As long as the mass remains below a certain threshold, the radiation from the nearby star will hit these easily boiled gases and hit them with enough energy that they'll escape. But rise above that threshold, and even the ultra violet radiation and solar wind particles emitted from the star within the solar system won't be able to kick those light atoms and molecules away. If if you're not, if you don't have quite that much mass, what you end up creating is a gas giant, a gas planet even even smaller than jupiter and saturn.