"The natural desire, typical to most of people, is to stay in a larger environment and to contact with more [than a] few human beings."Exactly right. I suggest a first crew of twelve instead of four (arriving in stages on 3 to 6 prepositioned landers from a ship in mars orbit.) Also, ownership has a huge positive psychologically effect and allows people to build huge malls and mansions for their mental health.
The landers, which are not built on mars, should only be considered temporary emergency shelters. Mars colonists, immediately after taking care of primary survival needs (local power and water) should make ISRU habitat construction a first priority. Building these insures they can repair them, making life support independent of resupply.
Habitat construction can be considered to have 3 overlapping phases... 1) telerobotic 2) suited 3) unsuited.
Telerobotic construction can begin before or after the first lander arrives from within a closed environment vehicle without a cumbersome spacesuit. It's duration is medium length. It involves preparation before a sealed environment is fully accomplished. The primary action may be trenching. Secondary would be covering the trench possibly over an inflated structure. This 'balloon' may come from earth for practicality of early construction but the goal is to only use local resources. Compressed bricks and loose dirt being the most likely construction materials (combined into vaulted ceilings?) Later, welded sheet iron may become popular.
Suited construction should be of limited short length to transition from phase 1 to 3. The primary objective is turning an unsealed habitat into a large sealed shirtsleeve work space. Plastic airlocks (brought from earth) may be used in early construction. Highway 1 is a sealed tunnel all personal habitats may connect to.
Phase 3 is long duration or more. Once it's safe to work on the interior without a spacesuit, that's what they'll do. Interior walls and floors would be added according to an owner's design preferences. A real toilet, bath and bed will probably be priorities, but getting sealed, privately owned spaces for all, should be a group effort all sign on to. This provides both redundancy and privacy.
Mission planning should have enough food prepositioned on mars before anyone landed so that gardening can be an individual pursuit done in leisure. UV protected plastic (thick enough to hold 10 psi) and live soil should be brought from earth as a starter kit. Enough so each colonist can discover their own green thumb. Seeds need not be restricted to dietary plants.
Mars colonists will endure hardships. People can. But they shouldn't have to endure stupidity imposed upon them. They will be bootstrapping an entire world. How valuable will that world be to mankind when millions live there? How short sighted would it be not to give them liberty right from the start?