I feel like a jerk to say that, but those who trust their email to an Outlook server almost deserve it. When will they learn?
Companies are having a hard time getting away from Microsoft. There are open source solutions for all Microsoft products, but employees often don't want to adapt. It's also a legal and insurance issue for some companies that require regular audits because Microsoft products have a better reputation than solutions from lesser known open source vendors.
It's less employees, who typically must do what they're told and more employers and managers. As well as an undeserved reputation vs other products, there's also "nobody got fired for buying Microsoft" and the idea that if something goes wrong, there is someone to sue. However, Microsoft has lots of lawyers and a deep war chest as companies have often found out to their detriment.
I helped a friend some time ago to buy a cheap notebook and setup Ubuntu on it for his daughter. Yesterday he showed me a letter from the school that she needs a Win10 Pro Notebook so that she can use O360 which all the lessons are based on.
Put win10 on a VM. Depending on your morals, you could don an eyepatch. (That doesn't really affect the point of what you're saying but fighting back always helps).
Schools should be pushed into platform-agnosticism.
Public schools should be almost forced into OS/FOSS (if they like their public funding, that is).
There. I said it. Does this make me a socialist?