Many people use proprietary software because they're forced to for work or social circumstances (i.e. banking and messaging apps), not by choice. In other words, they're socially engineered into it. Why trust software you can't inspect? Because it has a big brand behind it? Because no software company has ever betrayed the trust of its customers? Companies never do deals with shady partners that end up betraying them, and in turn their customers too? Transparency fixes this, and it can mitigate a company going rogue on its own product and customers.
Libre software can certainly suck in some areas of the stack, but at least I can do more than send an e-mail to an unmonitored inbox at a corporation where my ass doesn't matter as soon as they have my money. I'll get a form letter containing a response to what some random bot thinks I'm talking about, and my concern will not be addressed, even as a paying customer. In a world of software that I can inspect the code of, I might be able to research my way out of a tech issue. The contention is that even as a customer, I can't count on Microsoft addressing any problems I encounter. If you're already coming at me with "get ignored, go away" then what's the incentive to engage at all?
You're right that some sectors are ignored, probably because they believe they should be paid for providing certain things. Fair to have that opinion, but it's also fair for me to disagree with it, criticize it, and share that criticism.
I still give Microsoft software a shot from time to time, to make sure my understanding of it is at least semi-recent. But by and large, I don't enjoy my interactions with their ecosystem. Setting up Minecraft Realms and mitigating differences between Java and Bedrock was a PITA. The migration from Mojang was a pain. I did enjoy getting Bedrock for free with my transfer. That was a solid move that showed they understood it was a pain and were willing to part with a little revenue in the short term in the hopes I'd buy content in the long term. (I did, for the record.)
But that's video games. I don't mind them being proprietary because I'm there to have fun. As long as it's not chatting over the network or doing analytics and other shit, I'm fine with a game not coming with source code. But I also love that gzDoom, darkplaces, TADS, LÖVE2D, TIC-80, and other open engines exist where people can bring their own creations to life in a non-profit environment. Microsoft itself started in a bougie garage, they ought to appreciate the spirit of DIY.
I've paid for things so it's not like I won't buy anything. My experience and view is not any less deserving of expression simply because it's less popular, though. There are plenty of people out there similar to me in distrusting Microsoft and other big tech companies' software. Minecraft isn't perfect, it has analytics and a forced word filter, and no way to self-host a Bedrock server. None of those were a thing when I bought it back in 2011 or so. They want me to pay for a Realm for that. And I did, for a little while, due to family members wanting to play, but I realized I could host it for cheaper. Eventually we stopped playing anyway, so I didn't have to worry about it.
Most people simply don't care about software freedom, and chide and ridicule those who do. Unsurprising, but still no less disappointing when encountering it among those who like to develop an air of distinction and taste but come up lacking in conversation. If they care so little, why be shitty to those who do?