There's also a "smarter, not harder" aspect, too. Looking back into history, NASA originally thought of the concept of a huge ship that lands and takes off from the surface of the moon. And then they calculated how much that would take in terms of thrust and fuel. IIRC, it took more than a lb of additional fuel to each lb of mass going to the moon, let alone the needed thrust. It was not a linear relationship. And going to Mars is even worse.
That's why instead of a massive body to go to the moon and back, it was modular, and only the tiny command module was designed to get back to the earth's surface.
It's a massive problem.
Another "smarter" thing to do is to not have one single body launched. SpaceX has gotten proficient at orbital connection, right? So instead of one massive rocket, launch two smaller ones. Or even three. Have a command module, then a living module, and perhaps a rocket module launched separately. They could pretty easily do this in a day.
And one more "smarter" is to add complete booster rockets. Like Space Shuttle did- and it's pretty common for launches outside of earth orbit these days. This is the one that is probably the most curious thing now- SpaceX has done this already. They have launched rockets where the two side booster rockets landed near the launch pad, and then the main segment landed on a barge in the Atlantic.
Basically, there are multiple ways to the solution over the single out and back space craft.
