To send three men to the moon with a little lander and rover they had to build the biggest rocket in history, it is just not practical to make the equivalent but scaled up to reach Mars or anything else in our solar system.
To get to the moon takes a week or two or three to get there, do some stuff and come back. A trip to Mars is going to take years because even if you went there and came straight back that is going to be more than 12 months, but of course who would go there and do nothing but look and then come straight back?
Flying there with robots and setting up bases with unmanned systems and using a nuclear powered tug system to fly there under power all the way there and all the way back will speed up transit times and actually make conditions in deep space more tolerable because with a nuclear powered ion engine or something similar at least you would have micro gravity creating some sense of normal where there is an up and a down.
The real difference is that anyone going to Mars is on their own and there is a very good chance someone will die.
Such things get people upset, but how many people die every year still trying to climb Mount Everest?
I like the idea of space travel for people because it demands recycling and reuse... which is the opposite culture on earth thanks to the US and big business wanting to sell you something you don't need or want.
The point I am trying to make is that we are going to need to build space ships in orbit... in space and they are going to take multiple rocket launches from earth to assemble them and once assembled they can be sent towards Mars or some other destination but when they reach their destination putting them in orbit of the object they are going to would be easier than landing them... so these space ships will also be space stations and you might send other landers and space stations before you send people just to set up a landing area and perhaps even start producing water which is rocket fuel and oxygen so by the time you send people there they have the resources to live for quite a period of time if needed so if there is a problem things can be sent to bring them home.
3D printers on the small scale to make parts and on a huge scale to build shelters out of local rock material will make things more comfortable and safer, there are lots of technologies that need to be working well before we go.
It is all fine to make resuable plastic containers for things only to get there and find they shatter and are fragile in minus 60 degree temperatures...
Being able to get there in a reasonable time is the first problem to solve but there are countless other problems that also need to be solved like growing food and recycling human waste... all of which are technologies that would be useful here on earth.
A 3D printer that uses plastics that cannot be recycled to make things that are useful and when no longer used can be broken down and 3D printed again into something else to be used would be as useful here on earth as on mars or in space.