So SpaceX's [Red Dragon](https://en.wikipedia.org/wiki/SpaceX_Red_Dragon) is unlikely to ever fly. But if it had, what would it's realistic payload to the surface be? How significant would the payload penalty be if the capsule itself was built to maintain an atmosphere, to allow use as a room, when people arrived? (Life support being brought later)

I ask this because the initial payloads talked about were 1T (in 2016)... But curiosity was 900kg and landed by a sky crane. So surely Dragon would be better? Especially after Falcon Heavy had a 20% capacity upgrade.