The way people make money on obscure PCBs and other parts is that they typically have a warehouse in a cheap location (country side / poor part of a city). They then list everything they have (1000s/10,000s of items) in online catalogs / eBay. They put very high prices on items (close to a 1,000% gross profit margin) so that when they sell an item someone urgently needs (production / science / medicine / government / you name it) it generates enough $ for them to pay for their costs as well as generate a profit.
Trying to do this as a private person with very few items is not a very realistic proposition. Most of the many items these re sellers (tertiary/secondary market) stock take years to (or will likely never) sell.
This is why I typically recycle odd PCBs. Last year I bought a P233MMX that was full of echo cardiogram PCBs from the late 1999s: completely useless and near impossible to sell.
I remember ISDN from the mid 1990s in NL but it never really caught on from what I remember. Only businesses, schools and a few private households subscribed: it was pretty expensive albeit a lot faster than PTSN obviously. 😀 I think cable TV internet hookups destroyed it pretty quickly because people subscribed to that bundled with TV for a fixed price with unlimited bandwidth.
