Technical Challenges
While humanity would benefit greatly from a colony on Mars, the technical challenges to get there are enormous. Food security, radiation mitigation for the trip, the stay, and the return to Earth, a habitat with a breathable atmosphere... All of these problems need to be addressed before anyone can live on the surface of the Red Planet. While space agencies around the world have been sending people to space for over fifty years, only a dozen people have ever been beyond Earth's protective magnetic field, and only then for a very short time. Even still, the Apollo astronauts suffered from headaches and cataracts (Letzter, 2020). Interplanetary space is awash with high-energy particles, from the sun and other stars, which would destroy a potential traveler's DNA. Strategies would need to be developed to deal with this before anyone could even live on the moon, much less a planet as far away as Mars.

Nations which collaborate on International Space Station experiments have been working on techniques to grow enough food in confined spaces to make it self-sustainable (Herridge, 2019). Tests are being conducted on both hydroponics systems and Moon and Mars regolith (soil) facsimiles in order to perfect agricultural practices for self-sustaining colonies on foreign planets. Growing their own groceries on a long-duration spaceflight, or in a martian habitat, has the added benefit of regulating the oxygen and carbon dioxide ratios of the atmosphere inside the living space of any future explorers or colonists.
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Future Martian Habitat (maybe...) (image by ESA/DLR/FU Berlin/G Neukim/New Scientist)
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Mars Food Production Testing (image by NASA)
 One of the largest technical challenges will be the construction of a durable structure for permanent living quarters. Researchers have been looking at Martian lava tubes to provide a rigid frame for habitat construction. Lava tubes form from volcanic lava flows. As the lava at the surface cools more quickly than in the interior, it forms a crust over the flow. This tube hollows out after the eruption, leaving an empty tube. These lava tubes would be excellent protection from radiation, and from micrometeorites that constantly impact the Martian surface (Paris, et al, 2019). Because the surface gravity of Mars is about a third that of Earth, these lava tubes should be much larger than those found here, providing a rather spacious habitat for those who live in them. According to Paris, et al, if these tubes were supported, they could possibly be pressurized, providing an enormous habitat for a large colony.

The technical challenges would be great, and the endeavor would very dangerous for those willing to move to another planet, but the benefits would be greater than we could possibly predict. And these benefits would apply to all of us, from an abundance of materials for greener energy production, to agricultural practices that could be utilized in urban settings, to spin-off technologies that could revolutionize society.
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