Although to say that I'm not a fan of Microsoft would be an understatement I'm not telling you that its impossible to find an acceptable windows environment or impossible to prefer your windows environment. I am making a handful of much easier claims.
- Objectively if you you $150 to spend then spending $112 on the OS leaves you so objectively worse off than spending $0 that its hard to justify the retail cost of a windows license even if you prefer the windows environment. In essence the claim is that windows isn't so much better than pi + windows is better than 5x the computer + linux. Microsoft agrees which is why device makers for cheap devices have historically been able to get a lower per unit than for more fully loaded devices even if the windows sku they shipped with was a less featureful version.
You can't get an acceptable desktop machine for $89 to compare to your $35 rasberry pi. Such a machine will likely be underpowered, it will use 30x as much power, and it will be more likely to die relatively quickly.
Average hard drive lifespan is 3-5 years of use if I recall correctly. Many drives especially if used relatively less may in fact last longer but the average user is less likely to experience hard drive failure insofar as they trash the entire computer before it fails or in fact HAVE experienced it but in fact experience it as "my computer doesn't work anymore" rather than specifically understanding which component failed. Especially if by the time it fails a new machine is objectively desirable.
If you buy an 8 year old machine it would be remarkable if it lasted more than 2 years more during which it would have been liable to use $80 more electricity based on 20 hours of weekly usage.
In brief if you spend $170 and find some dude on craigslist with a particularly good deal you might be able to have a slightly worse or slightly better experience than someone with $35 in their pocket can have any day of the week and twice on sunday.
In short people buying small cheap computers like the pi aren't just too stupid to use craigslist they are making an objective choice with reasonable tradeoffs.