Isn't that true for anything? Some people will sell 5yo hw in almost mint condition, whole others treat their hw like ass and it's garbage after two years already.

The problem with used Macs is that they're still really expensive, and if you want to only run them with Apple software, the support duration is limited (especially true for phones, even more for Android ones). You can pick up used Thinkpads or Dells in great condition for very cheap after a few years.