We live in a complex world, with complex problems requiring complex solutions.
Arguably that wasn't always true. We've evolved in a much simpler environment, where our simian instincts were good enough. But saying "good enough" is already an admission that things weren't so simple back then either; it's just that for the longest time we could muddle through.
Either way, that's not the case anymore. Which is why scientists are always so cautious in their statements, and carefully qualify every claim they make.
Too bad our instincts have remained the same, and cautious, careful claims sound suspicious to our big monkey ears.
What scientists say: for X to work, it would take countless pieces falling into place just so, clicking together perfectly and working without fail for who knows how long.
What most people hear: so it's a done deal, right? Nothing can go wrong. Let's do it!
Did I mention most people are also incurable optimists? And by that I mean "wilfully oblivious to anything negative". But don't get me started about magical thinking now.
What else scientists say: to save the planet, literally everyone has to take unprecedented measures on a humongous scale, in less time than it takes to raise a child.
What most people hear: oh, it's all right then, we're saved. Nothing to worry about.
Think sci-fi writers have no sense of scale? Meet the readers. That's how the dream of space colonization stayed alive for so long, when it's even less plausible than I thought. And I had actually paid attention.
Most people don't want to. It tends to reveal the complexity of the world. And that frightens us more than any dangers.