And what people here are telling you is that Linux Mint is now work level commodity out of the box. And it will only get better with time.
Why would you pay money into a system that is designed to make you - pay money? Forever. With viruses. With no productivity gain?
And regarding the money, since computers come with the OS (Windows) already installed, you are no longer paying them any money. It is fully paid for. So if you install Linux, you are replacing something already installed and bought and paid for. Only a hobbyist would do that. The average person is as interested in doing that as they are in replacing the engine in their car when the current one is just fine.
But as I said in an earlier thread, I have two desktops in storage that I may give this a go with. My “inner hobbyist” has not completely dead. Who knows? If this is better than Ubuntu, I just might run with it.
“install it on a computer that is already working just fine”
I would not characterize any computer running a recent version of windows as “working just fine.”