I think I read that below 7 degrees winter tires starts to become recommended in front of performance summer tires. The closer you get to the point of freezing the larger the grip difference between summer and winter tires gets. Around 0 degrees the difference in grip is quite large even on dry asphalt.
I don't see why someone would buy a rather expensive car and not use money on winter tires. Its great for your own, you passengers, you car and others safety.
You are also saving thread wear on your summer tires, so its not like its money out of the window.
Rims are also worth something when used so there is no large economic downside in a buying a set for the winter.
The upside can be quite large tough.