That's a vast understatement. Don't forget expense and time! Orders of magnitude more.
I don't think there's any realistic way of getting a sustainable base on Mars without doing it first on the moon. On the moon you can learn from mistakes. On Mars you die from the first mistake.
The martian atmosphere may not provide a lot of radiation protection but it provides way more than you get on the moon. And again, if you've got access to ice, you can use it to fairly easily create radiation shielding for your base.
It could be a situation where difficulty of receiving aid from Earth is offset by a lower risk of things going catastrophically wrong.
That said, if I was planning a mission to Mars, I would want extensive redundancy throughout all of my systems. One thing to keep in mind, a modern Mars mission does not need to be mass-limited in the same way that the Apollo missions were. SpaceX has already greatly reduced the cost of putting mass in orbit, and if Blue Origin can actually make New Glenn work, then you are looking at a substantial reduction from SpaceX's current cost-to-orbit.
We have yet to know what can be produced from Moon materials. A couple bags of rocks tell is pretty much nothing about the variety that may be available. After all, what would a couple bags tell you about Earth?