>for a fair number of people we know, it is the primary living space.
Are you talking people stuck in their cars for most of their non-work and non-sleep hours or about homeless people?
People who are homeless by choice. All climbers or other outdoor athletes for whom living in a city is onerous.
A friend who got divorced and basically moved into a Prius (that's extreme), but when she needs space to get work done, she takes an AirBnB or she might sublet here and there for a month or two. She's a photographer and just brought her expenses way down so she could spend most of her time climbing.
Another friend works in rope access (i.e. rigging for wind turbines, cell towers, sports events, etc). When he's on assignment, he gets a per diem and if it's far away, lives in a hotel. If it's close enough, he lives in his Sprinter van and pockets the per diem. As a general rule, his goal is to work as much as he has to to keep benefits and spend the rest of his time climbing.
Another friend is a hardcore ultrarunner. She is a software engineer for a well-known tech company, remotely from her van. She puts in a few days of work, then goes and runs 100 miles in the snow (seriously) and then back to the van to crank out code.
One friend now has two kids, but before that he spent most of his year living in a van despite owning two houses. There are two others who are more friends of friends or acquaintances who have enough money to buy houses, but mostly live in their vans. One actually started an environmental foundation with something like $300,000 of his own money because he was getting tons of sponsorship money, but was living on $20K/ year in his van.
I could go on. There is a sector of our society for which this is a relatively normal choice. It usually comes to an end when they have kids.
