The original idea, about sixty years ago, was that we would settle Mars, and be able to flit between Mars and Earth frequently. The reality of the enormous cost of space travel dawned about the seventies. The original understanding was that the atmosphere of Mars was unbreathable, (correct) but the atmosphere exerted enough pressure that a pressure suit was not needed. This is also untrue.
Two points emerge:
Migrants go to Mars go on a one way trip, never to return. In the early years of the settlement of north and south America, and Australia, most migrants took a one way trip.
Martians will live in pressurized surroundings, but will need to leave pressurized buildings frequently, so they need a pressure suit that can be put on nearly as easily as putting on an overcoat for a cold day on Earth.
Food is a serious problem. Plants will grow in pressurized tents of clear plastic, carbon dioxide pumped from the outside atmosphere. Sunlight delivers about half the power per sq metre on Mars than on Earth. The worst problem is cold. Large arrays of solar water heaters, connected to a large heat storage, might work. If uranium is found on Mars, then simple atomic piles can heat buildings. Such piles will be similar to the legendary squash court reactor in Chicago just before the atom bomb project started. Solar power can supply electricity.
In the early years, unmanned vehicles could deliver grain and sugar from Earth to Mars, for a cost which is merely exorbitant rather than overpowering. The vehicles do not return. The sugar could be used to power cellular reactors to produce fruit juice, milk, eggs, the last two being yolk and egg white separately. Milk leads to butter, cheese and yogurt. More advanced cellular reactors than we have at present could provide food with texture such as vat grown potatoes, apples and similar. Shell fish and small fish could be grown in tanks, from feed made from grain and vat grown materials.