[publius911]

“I’m not going to install it - but just out of curiosity - is there any upside?”
Of course, better security. Also, no upgrade cost as long as you have it.

Not quite true.
Like a drug dealer, you get to download Windows 10 for "free." But after a year you must pay around $100 or more, depending on the version, to keep using it.

That's what I understand.

[Advil000]

No. That has been debunked over and over.

MS has repeatedly said the updates are free for the lifetime of the device.