If we cannot support humans on the moon,
it seems less likely to support humans on Mars.
Water on the Moon remains unconfirmed. (It could be confirmed with a relatively inexpensive unmanned landing mission to the lunar poles.) There is little or no carbon dioxide there, either, and there is no other source of carbon. You need to use rockets to brake to a landing on the Moon, hence additional fuel.
For a relatively small addition in escape energy, you can get to Mars, brake to a landing using its atmosphere, and have all the chemical components at hand to begin industrial operations - from what we know already.