One thing to understand. You have to do something to allow a virus to get in a computer.
However a computer worm will detect and infect by taking advantage of vulnerabilities that have not been fixed. There is no actions necessary by the user. If you do not update to an operating system that is getting updates you will be opening up your computer to being taken over to spam and infect others, your computer can also be commandeered to mine bitcoin, and if your foolish enough to do financial transactions you can be subject to fraud.