When Windows decided to auto update in the middle of an important meeting without any prompt;
when I download files overnight and the fan takes off at midnight by its telemetry process;
when it gives me a full screen ad trying to change my system settings and stops me from entering the system on time;
when the system starts to integrate with ads from the browser to the taskbar.
It's not because how good Linux is, it's because how bad Windows has become.

So I left after my little checklist of must-to-haves is fulfilled. With no regrets.