Well... DX12 isn't actually "far away" by any means (less than a year, 2-3 years for games to drop dx11 entirely) and a lot of people are going to be feeling pretty stupid for not saving themselves $120 over something they don't even remotely understand.
Anecdotal posts like that are exactly why they have attempted to remove this upgrade decision from as many users as possible. You think you know better because you've been lucky in the past, but you have no clue what kind of risk you are actually putting your data in.
It's classic confirmation bias. This is the same stupid argument people make about not installing A/V software on their computers.
"I've never been infected" How the fuck do you know?! Not all infections are of the "popups and crashing programs" variety (and haven't been since the 90's).
A little "phone home" for telemetry (or data processing in Cortana's case) VS. a massive security risk by using an unpatched OS... yeah... nice decision you made there.
I mean... How stupid do you have to be to actually think that your data is somehow safer on an unpatched computer?!