There are already good answers but I'd still like to contribute something.

Including the simple security practices that are still better than windows even after all this time, and all those viruses, I also believe the issues are largely social.

I believe that the main factor is the diversity of distros. This raises the labour involved in making sure that a virus has what it needs to spread. This combined with the demographics of linux users who are not as likely (imho) to click on a dodgy email or generally put themselves at risk means that the success of a virus is further.

People are also arguably more motivated to attack windows.

There are already good answers but I'd still like to contribute something.

Including the simple security practices that are still better than windows even after all this time, and all those viruses, I also believe the issues are largely social.

I believe that the main factor is the diversity of distros. This raises the labour involved in making sure that a virus has what it needs to spread. This combined with the demographics of linux users who are not as likely (imho) to click on a dodgy email or generally put themselves at risk means that the success of a virus is further inhibited.

People are also arguably more motivated to attack windows.