Let's not conflate something "working" with something able to receive support from the manufacturer. If I have a car from the 1960s, I'm sure it will work, but beyond the legality of some components, if something breaks, if the manufacturer even exists anymore I would be lucky that they would help support it, and if they did, I would have to pay a large sum of money for the support.

If a customer wants to use Windows XP, they can, but if a customer wants support for it, they can pay Microsoft a lot of money for it (and I think some actually still do).

Besides, don't forget that businesses do need to make money. Are you suggesting that Microsoft should have supported/should support Windows XP forever, for free?