I still remember when my old man drove 20 km with a tractor and trailer 20-25 years ago to pick up 120 m2 of paving stones (for free) and then laid them in our driveway.
Another example: I was recently at the hardware store for 10 m2 of roof sheathing for a shed/shelter and they wanted 300€. The salesperson said it absolutely had to be tongue-and-groove and who knows what else. In the end, I got the 10 m2 for free from the boss, but had to go to work twice with a trailer to load the stuff. Even if the wood might not be top quality and lasts only 15 instead of 20 years, it was free at first.
Sure, not everyone is skilled at handiwork and/or has the equipment, but almost everyone has a shovel and a pickaxe, wheelbarrow. Of course, you don’t have to dig the foundation pit with that, but hardly anyone wants to pave or lay curbstones themselves anymore.
What I ultimately want to say is that the mentality of those wanting to build must also change, and smaller steps must be taken.
In the past, building a house was a reward for the sacrifices you had to accept for it. And not a by-product you just hand over to a general contractor alongside home office. And the main personal effort consisted of finding suitable financing, even though you can also save a lot of money there.