Stop buying their software? Windows 10 is free, nobody has to buy it.
Just because you didn't give them money up front, doesn't mean there aren't other costs associated with using the products. One has to ask how long before microsoft starts selling advertising services to customers that can't be blocked because its the OS that’s feeding you the ads? Only way out is to buy enterprise edition? Guess what, that costs $200 per seat, and unlike past generations of PCs, when you buy a PC now, you're getting the free version of windows, so now that $500 PC is actually going to cost you $700 to get what you used to get. You as the tech support guy need to warn your friends and family that this is what they have signed up for with windows 10. Beyond that warning, refuse to support it, and tell grandma that you would be happy to install Ubuntu or Debian, or some other such that really *is* free.
As long as you keep trying to do free tech support for microsoft, they're going to keep shitting on people like you. If the product doesn't work, why are you fixing it for microsoft? tell the people that if they have trouble they need to contact microsoft for tech support, and when microsoft refuses, that's when you offer one of the Linux variants.