It's free if you're willing to break the EULA. I haven't paid for it. Just used some Win 7 CD key I found online and it activated.

Not even break EULA, just download from Microsoft and install without activating.

That is breaking the EULA:

"You are authorized to use this software only if you are properly licensed and the software has been properly activated with a genuine product key or by other authorized method."

Ah, you're right. Wow, that EULA is very different from the reality of how people use it, and MSFT makes no attempt to enforce it.

Ehm, I guess you have never heard about BSA raids, right?

Edge is cross platform.

That's a technicality - who in their right mind is going to choose edge on other platform if they are not already used to it from Windows.

Enough users to justify the salary of the teams making it happen.

In practice it has been free for home users for many years. I assume the only reason they still keep up the facade that Windows costs money is so they can sell it to OEMs and volume licenses to businesses, which still makes them big bucks.

It only seems free for home use because the activation key for the home version is embedded in NVRAM of the machine by the OEM. You pay the OEM when you buy the machine, and they pay Microsoft.

You pay the OEM once, for a Windows 7 key, and then you run on that -- because it keeps working, with Microsoft's implicit authorization -- for the next 15+ years. They 100% would not let you do that if they cared to charge for Windows like they did in the pre-Windows 8 days when Windows was the product and not the user's data.