Why would you upgrade? In my experience upgrading works perfectly only a fraction of the time. Besides, I don’t want anything to change and when it does, I am interrupted and forced to do things differently. This explains the survey data provided below which suggests that women are less likely to upgrade than men.
Upgrades are an intrusion. Malware, spyware, and viruses are intrusions as well. While there are programs that keep track of everything going on (services running, etc.) they require far more sophistication than most users are able to provide. And how can you really know anyway. One of the most damaging phishing/malware exploits mimics a Windows update.
It has become the Catch-22 of computing IMHO.
All that said. UPGRADE. and get used to it because it is part of the landscape of computing – at least today!