I'm just talking about doing the stuff that anybody can figure out to do. You purchase materials, and you hire craftsmen to do the hard stuff. I'm also not talking about getting a house for free, I'm talking about boring house prices that track inflation rather than exciting house prices that track bitcoin.
Well you can always be the general contractor and do just that for a standalone home. Shop around and hire the workers for each part. Most people don't because it takes time, work, and knowledge, so they would rather pay someone.
Alternatively, you can get a new prefabricated home built and delivered for about 100K or less.
I think a lot of cities have zoning regulations against doing that, but it's common in the country and counties.
Where I think you do have a point is the land. That's often the expensive part. It's not as wild as Bitcoin, but it certainly does follow the market.