Honestly, please explain.

I know SaaS, but I don’t see how that is relevant to Windows 10 and its maintenance. The OS works without requiring an Internet connection, so it’s not relying on cloud computing for much of its functionality.

Ending support for an OS is also totally normal, many FOSS OSes do it too. Whether you paid for it initially or not honestly makes little difference, at the end of the day someone else has to expend their own time to fix something for you - some might do so for free, while others want to be paid.