It depends, if they only use a browser,solitaire,image viewer and video player then the Linux equivalent are very similar or better. If they use some exotic software then I agree with you.
But keep in mind that there are people that will have no idea that you changed the software, I was called by a neighbor to check why his laptop has no longer sound, somehow he muted Windows without knowing(maybe he hit some keyboard shortcut). With this low skilled people there is o retraining cost because their skill is already close to zero
If it's not always more work to retrain people with no tech skills than to not do it, will you retrain every such person in the country? You're already not doing it, so this won't increase your workload at all.
I am not a person that converts people to Linux, the entire thread was about when it is right to help a family member by installing Linux on their broken system, see above the conditions i think are the right one. The fact I could convert a random person to free software is not valuable enough to me to was 1 hour of my free time(yeah I am selfish).
That's my point. It takes an hour of time to convert someone to Linux. It takes 0 time to let them get their tech support from the local store. 1 hour is more than 0 work, even for a family member.
You also have to account for the fact that other people might think you're lazy or self centered because you don't want to spare some time to at least try to help them. Not saying that you're a bad person for refusing to provide free tech support, but your math is not entirely flawless.
Unless having a reputation for being lazy and selfless leads to more tech support calls, I think the math still works out on this being the least amount of work to get rid of tech support calls.
Whether this is a good idea or not is a separate question. Personally, I help my friends and family when I can.
But keep in mind that there are people that will have no idea that you changed the software, I was called by a neighbor to check why his laptop has no longer sound, somehow he muted Windows without knowing(maybe he hit some keyboard shortcut). With this low skilled people there is o retraining cost because their skill is already close to zero