From PC Magazine:

Microsoft Needs to Get Serious About Its Windows 10 Upgrade Problem
By October 2025, more than a billion PCs will be running a dead operating system, leaving many computers vulnerable to malware or headed for the trash. What's Microsoft going to do about it?

The Windows 10-pocalypse is a short two years away. On Oct. 14, 2025, Microsoft will stop issuing security updates for Windows 10 PCs, at which point most of the world’s PCs—about one billion computers—will be running a dead operating system, like Windows XP. And most of those computers can't upgrade to Windows 11.

Microsoft Is Abandoning Most PCs on the Planet
Half of the readers of my Windows Intelligence newsletter are still using Windows 10 on their primary PC. The one billion estimate comes from two sources: Microsoft, which has said there are more than 1.4 billion Windows PCs, and Statcounter, which shows that the vast majority of PCs on the planet—more than 70%—run Windows 10.

Worse yet, this isn’t like when Microsoft stopped supporting Windows 7. Those PCs could upgrade to Windows 10, but this time around, many Windows 10 PCs don't support Windows 11, at least not officially. If you can't afford to buy a new PC, you'll be left out in the cold after Oct. 14, 2025. From a security perspective, it’ll be as if you were using Windows XP or Windows 7.