Remote activation can only happen when when there is something on the victims pc to to allow it to run. You can't magically run things remotely on someone's oc without tricking them into installing something first or it finds an exploit into something they already have installed. Dude go put on your little tin foil hat. Paranoid.
So that whole "wannacry" thing was just a made up story by people being paranoid and nothing to do with exploits in Windows Operating System services then? 
Given that there have been so many "0 day exploit" attacks in the past... and no doubt will be more in the future... being a little bit "paranoid" when it comes to valuable (and easily "stolen") digital assets is not necessarily a bad thing.