They do not cost 10x as much as devices with soldered RAM and SSDs.
When I built PCs in the late 90s, the BOM included motherboard, cpu, graphics card, sound card, nic, sometimes a parallel port board, memory, hard disk, etc. At this point, it was only really feasible to repair modules that failed, few humans with the skill to replace a component would do so due to the economies of scale and cheap price.
Now, it's motherboard, cpu, memory, disk. The cost is much less, but most repairs are replacements of the mainboard or disk.
For most laptops, there's a tiny motherboard with most of the functionality integrated into a few modules. The only things that get repaired are memory and battery.
For the M1 Macbook, you have one of the highest performance devices on the market selling for $899 at 40-50% margin. I just bought similar Dell and HP units in quantities over 50,000 last fall for $100-150 less (probably 6-8% margin to the OEM), with inferior battery life, disk and cpu.
The M1 is a fresh design on a new iteration of an arch by very smart people and its likely that there are far more factors at play than presence or absence of sockets in terms of determining profitability.
What we are trying to do is determine all things being equal how much cheaper can the same machine be with and without replaceable parts. I don't have any numbers either but I strong doubt its 2-10x cheaper.
Look into Apple's M1.
Phones have been system on a chip since the dawn of the era of the smartphone and few computers are. The difference between repairable and not is the difference between glue and screws and sockets vs solder. You have basically misunderstood everything.
Computers have gotten a lot faster, that is why "spend" has kept up.
And you seem to suggest that early smartphones were already as fast as an M1, because they were "systems on a chip". That is not the case. Not all SoCs are the same, more and more things have been integrated over time.
And sockets take up space, making for thicker smartphones. People don't actually want that.
>And you seem to suggest that early smartphones were already as fast as an M1, because they were "systems on a chip"
I never suggested anything of the sort. My point is that smartphones have always been integrated and computers have usually been more discrete. You said the drop in price or increase in value for money has to do with integration. This doesn't appear to be correct because computers have been party to this without largely being integrated in the fashion you suggest.
The M1 is so fast and efficient because it combines even more stuff on a single chip.
My dad replaced a defective memory chip on his IBM PC XT.. but the computer cost the equivalent of $12k.
I’d rather throw away a dozen modern laptops than fix one that costs 10x.