> Malware targets Windows because that's where the users are. If the majority of people swapped to e.g. Mac or whatever else, then you'd see the majority of malware start to target Mac.

Even if this is true, it doesn't change the calculus for the individual company. If they switched to something else while everyone else is still on Windows, now they're using something with less malware targeting it.

If everybody did that then maybe more malware would target the other thing, but that only matters if they mostly actually do and that actually causes there to be more malware than there is on Windows.