Edit/Preface: I made this post just in response to the point about email, but I think there's a broad contention here. Regarding email, just be clear, I think it's a poorer example then many because it really can be offered for a song. The complex bits are highly amortizable, it's standardized/static/federated, and the fundamental storage/memory/cpu/bandwidth per normal user is nearly zilch. Business models are a lot more flexible with all that. There are other services where it's a lot more arguable that "free" does mess up the market.
But only to a point, I think it's actually become somewhat overrated as a principle. Many of the most valuable subpopulations of any market are made up of people who know perfectly well how financial reality works, and that things that aren't free to offer need to get paid for somehow. There was a period where often "free" really was essentially free, because it was VCs pissing away money, and it was perfectly rational to use it. Or there were volunteer efforts while people tried things. Much of that of course was not sustainable, and the compromises that come with it long term are a lot more visible and widely known now. There is backlash to be seen against "free" models in plenty of areas. Sure, much of the market may make the bargain, but that isn't the same thing as there being no market for something that has a higher sticker price but offers privacy and quality alongside that.
--Original Post--
>Do you think it's possible to convince friends and family to start paying for email as well when they already get it for free?
Yeah, pretty trivially, so long as their needs are normal. Email is just such a fundamentally light service for most usage that it can be covered easily. These days I do most of my domains through Gandi.net for example, and each domain includes 5 mailboxes at 3 gigs a pop. In actual practice is just hasn't been hard to sell friends and family on the value of having their own domain for email. It looks good/personalized, it means they can have the exact handle they want rather then johndoe5712038123871@gmail.com, tying into that they can have easier mailbox splits, it means they can keep their email if they move to a different service, and $16/year or less simply does not break the bank. I've set up a lot of friends and family at this point, and nobody has ever had any difficulty grasping the advantages of any of these in this day and age. Many have for example lost old email accounts before due to moving services, and "this can be yours for the rest of your life regardless of where you go" is quite compelling. It's not even just companies going out of business, it's not hard to pull up stories of Google alglorithms banning accounts for unrelated stuff for example, and it being nearly impossible to rectify.
The real obstacle isn't some minimal payment, it's that it's seen as more technically challenging, or they've simply never considered it at all.