I say this with compassion, not malice. Twenty-five years or more have passed since I installed Windows 3.1, I've never installed an anti-virus program, and I've never been infected by a computer virus. Why? I don't visit porn sites, gamer sites, or hacker sites, and I never open files sent by email, other than pictures. A LOT of people I know have the same experience. I know a few people, usually men going to suspect sites and women opening cute attachments in email, who have had to reinstall windows. So, sincerely, I make the observation that snarky comments do not exhibit Mensa membership nor reflect real world experiences by many satisfied users.
Hate to tell you, but I’ve been working in IT for 30 years. It is absolutely astounding how fast a Windows machine can get infected. Yes, I exaggerate about how fast a stock configuration, no add-on Windows machine gets infected, but not by much. Take a look at this from just last month:
http://thehackernews.com/2017/02/windows-smb-0day.html
“Last weekend a security researcher publically disclosed a zero-day vulnerability in Windows 10, Windows 8.1 and Server editions after Microsoft failed to patch it in the past three months.
The zero-day memory corruption flaw resides in the implementation of the SMB (server message block) network file sharing protocol that could allow a remote, unauthenticated attacker to crash systems with denial of service attack, which would then open them to more possible attacks.
According to US-CERT, the vulnerability could also be exploited to execute arbitrary code with Windows kernel privileges on vulnerable systems, but this has not been confirmed right now by Microsoft.”
They knew about this for THREE MONTHS and didn’t patch what’s nearly a top severity bug and security hole.
Your experience simply indicates that you’ve been very lucky. I suggest buying a lottery ticket.