Whoever you are, I have always depended on the kindness of strangers. — Blanche DuBois, A Streetcar Named Desire
As far as I can see there is no solution to the zero day exploit problem. Someone can always see what software you are running and wait until the moment a vulnerability is discovered and immediately attack you before you can patch. It is true however that most people will not be targeted in this way since there are many more benevolent people than malicious people (see above quote). In general websites are not targeted until vulnerable sites can be found with a web search engine, making it easy for a few people to find a large number of vulnerable sites.
Don’t know where I’m going with this post. Just that we are doomed to not be able to instantly patch.