> It's mostly about the number of humans competing to live in an area vs. how easy it is to get land in that area so that a new house can be built
What attracts people to a place is often all the other people there. The actual land area is not close to being a limiting factor, we only build on about 1% of it.
> why everyone doesn't just get a house (if someone can't afford a house, why not just upskill and learn how to build one? It isn't that hard
You've not followed Colin Furze, I see. Even his basic concrete and steel tunnel and bunker isn't "just upskill" and done alone, he's got a team.
Clearly you've also never gotten a line by line price estimate for a house where you could save €50k by doing the plastering yourself, like I have turned down.
Some rough estimates for the time it takes to learn the necessay trades; if you think these are unreasonable, ask yourself how come e.g. plumbers cost so much on callout, or how long after graduating you were still a noob at whatever your day job is:
* Basic construction literacy (plans, codes, sequencing): ~1-2 years (or 3-6 months intensive self-study + mentoring)
* Site preparation & surveying basics: ~3-6 months
* Excavation & earthworks operation: ~6-12 months
* Concrete work (formwork, rebar, pouring, curing): ~1-2 years
* Masonry (brick/block work): ~1-2 years
* Carpentry (structural framing): ~2-4 years to solid competence
* Roofing (structure, waterproofing): ~1-2 years
* Plumbing (rough-in + fixtures): ~2-4 years
* Electrical (wiring, panels, code compliance): ~3-5 years
* HVAC installation: ~2-4 years
* Insulation & air sealing: ~3–6 months
* Drywall installation & finishing: ~6-12 months
* Interior carpentry (doors, trim, cabinetry basics): ~1-2 years
* Flooring (tile, wood, laminate): ~6-12 months
* Painting & finishing: ~3-6 months
* Window & door installation: ~6-12 months
* Exterior finishes (siding, stucco, cladding): ~1-2 years
* Project management (budgeting, scheduling, subcontractors): ~2-5 years practical experience
* Health & safety compliance: ~3-6 months initial + continuous practice
Becoming individually competent in all trades needed to build a house to a professional standard is roughly a 10-15 year path.
A single person can reach "good enough to build a simple house" faster (perhaps 5 years if you skip the optional bits and keep the process count as low as possible), but quality, speed, and compliance will be limiting factors. And you'd need some person or people with all that knowledge to tell you which processes you could get away with not using, otherwise you'd end up with the house equivalent of vibe coded software.
This is also why houses in need of significant maintenence go for so little, sometimes even less than the land they're on.
Heck, if even just *insulation* from that list was as easy as you seem to think an entire house is, the UK would halve its heating bills as fast as its factories could make (or ports could import) foam.