Our biggest issue with trying to live off earth is the huge variety of bacteria we, and our food supplies, need to survive, versus those that harm us and our food supplies. FYI: You have more bacteria cells in you than you have of your own cells. By weight the bacteria is much less because they are usually much smaller. Any colony, unless it maintains constant back and forth traffic, will diverge. Eventually it's favored bacteria will be harmful or even deadly to people form other colonies. Add on top of that colony specific viruses, etc.
The SF ability to scan a body for harmful viruses, and bacteria then neutralize them when you go from one biosphere to another will be a necessity for anybody traveling between worlds, space stations, etc. It isn't the big things that will get you, but the little ones. Without the ability to find an neutralize harmful viruses and bacteria you couldn't travel. A colony on Mars wouldn't diverge to much to be an issue because of the high amount of travel back and forth, but one out at Pluto where travel takes much longer will diverge a lot more. Any humans that go to other stars will be effectively different species after a few thousand years. Our bacteria and viruses will be so drastically diverged we could only meet wearing space suits. Another thing is Mars is constantly being seeded with earth bacteria stripped off or upper atmosphere, along with some of our air too, and carried to mars on the solar wind. Yeah, bacteria get lofted up and carried about by the wind. When they get high enough, they get dragged off by the solar wind. The asteroid belt asteroids, Mars, and any planet or moon further out in the solar system without a magnetic shield will catch a few of them. Bacteria and fungus are remarkably durable. Spacelab, and the Russian space station both had bad fungal growth problems. They hadn't been designed to allow for cleaning up of all surfaces, inside and out. The Russian space station even had fungus growing on the outside. Read this and shudder:
https://science.nasa.gov/science-news/science-at-nasa/2007/11may_locad3 With the right precautions space travel will be possible. We just have a lot to learn.
When you think about this from a terraforming perspective, earth compatible bacteria will need to be seeded into the environment, and reinforced often to keep divergence down. Nanobots that destroy incompatible bacteria will be a necessity.
When you think this through, you'll realize that even time travel on earth is fraught with the same bio incompatibility hazards. So, yeah, medicine and biology is something that will need to advance greatly.
You are missing the point. They still grow in the ground, and they still need to be processed and transported, and the scale is still massive. Something that isn't going to happen on another planet. It's chalk and cheese.
You'd be surprised at how much food is grown using hydroponics.
Absolute rubbish.
We do not have the technology, not even an order of magnitude close, to enable a Mars colony to self-sustain itself and grow in case the earth got wiped out. They would simply die out.
If you think we do then you have no clue about the absolutely massive scale of manufacturing and process infrastructure required in the modern world to make everything you take for granted, and everything the Mars colonists would take for granted.
Such a concept of saving the species by moving to Mars is absolutely laughable in any time frame we can reasonably imagine.
Take the absolute simplest example (and there are literally hundreds like this) of a controller and for the solar panels.
What happens when it breaks?
Use some spare parts? Ok.
What happens when you run out of spare parts?
Manufacture your own? Using what? A magic 3D printer machine that makes chips and parts?
Do you know how many process steps go into making just one modern component?
How on earth (pun realised) are you going to recreate that one Mars?
Ya have to start sometime. Might as well be 2024. BTW, you should look up printing of resistors and diodes. Also look up resistor diode logic. GHz diodes can be printed. Something very famous used it.
In the early years chips may have to be imported, but some day an entrepreneur will establish Mars' first semiconductor fab, or maybe Apple or Intel will. In the long run it is massively cheaper to ship the machinery to make chips, and the designs than the chips themselves. Sure, mining and raw materials infrastructure will need to have happened by then. I expect that will get set up quickly.
I expect the mining and manufacturing that happens on Mars will be totally different than on Earth. This is because of lack of labor. It will be very highly automated and initially overseen by somebody who has the smarts and knowledge to fundamentally modify its processes if needed.
I expect industry exports from mars to go from very valuable commodities to manufactured goods when there is a sufficient variety and supply of materials available to make stuff on Mars. Mars' main market will be it's self, and the asteroid belt second. It has a much lower cost to orbit than earth has. The commodities that are not cost effective to be shipped back to earth will be stored on mars until somebody wants to use them.
For low cost from ground to orbit for durable goods and bulk commodities, I expect somebody will install a electromagnetic catapult type launch system. Olympus Mons is extremely high and would be out of most of a human breathable atmosphere should they create one on Mars. If they didn't, then it could be made almost anywhere. The atmosphere is so thin it doesn't even double the length needed. On Olympus Mons they could build a catapult that could put stuff into a trans Mars to Earth orbit. It then becomes a matter of catching it as it gets close to earth. An ion thruster package on the front end could slow it considerably and guide them into groups so they end up in earth orbit in close proximity to a bunch of other loads for easy pickup. So what it takes a few years to get there when you are talking metals and other long term durable commodities. Food stuffs is a different issue. Eventually earth's population will outgrow earth's capacity to produce food. At that point they will be importing it from space. A catapult could launch it so it could be grabbed by a continuously orbiting set of ships that always travels between Mars and Earth and never stop at either planet.
As for 3D printing. 3D printing of some replacement parts for the space ships is viable. This includes metal parts as well as plastic ones. Carrying along spares for everything that may go wrong is costly, but sending a few 3D printers, some raw material, and generic controller boards can make replacements for used up spares, or for parts without spares. Also sending spare parts to Mars is expensive, so as soon as the raw materials are available, spare parts will be made on Mars. Before then bulk raw materials and 3D printers can be sent to mars during non ideal times so parts can be made on Mars. You won't be able to 100% predict what you will need. So to have the resources to make a new design right then and there is a good policy. They can also be used for making manufacturing plants for making the robots needed to do the work. For parts that can't be made on Mars, generic parts can be shipped. Stuff like universal logic controllers that can take the place of many different ones, or they could standardize on a set of them, and program for the target use. A batch of the main processor boards, cameras, and sensors used in Teslas would be great for controlling made on Mars automated rovers, and human carrying vehicles.