No, people panic because an army of cybermen who want to 'upgrade' you or a gang of weevils looking to rip out your throat and eat you is terrifying. And we don't know what's going to be coming next. There's all of space and time to contend with, and how can we prepare people for every possible eventuality when we don't even know what might be next? How do you convince people to keep living normal lives if they've the knowledge that there are constant threats from beings so far advanced or so numerous or so plain alien that some days it's pure luck we manage to keep the world from ending at all?

I'm not saying we should try and convince everyone who believes in aliens that they aren't real. But it's hard enough -- it was hard enough just to maintain control of the Rift and manage the threats that got through, without having to deal with public paranoia and misinformation and souvenir hunters and vigilantes and...it'd be chaos.

Not all leaders are like that. Some of them want to do good, protect people. Some of them are worth believing in.