That's probably okay - we are programmed to play along, and this approach proved to be a smart evolutionary move. A degree of trust is essential to advancing our civilization at a reasonable pace; and paradoxically, despite the apparent weaknessess, the accelerated rate of progress makes us stronger and more adaptable as a species in the long run.
When it comes to the online existence, our attitudes seem drastically different, though: we only joke about the idea of using the evil bit - and yet, we are perfectly comfortable that the locks on our doors can be opened with a safety pin. We scorn web developers who can't seem to be able to get input validation right - even though we certainly don't test our morning coffee for laxatives or LSD. We are being irrational - but why?
Perhaps the reason is simple: the mankind had thousands of years to work out the rules for social interactions in the real world; societies collapsed, new ones emerged - with an increasingly complex system of moral values passed from one generation to another. The Internet is much younger in comparison, and in the end, very different from what we are accustomed to: your neighbor will not try to sneak into your house, but may have far fewer qualms about using your wireless network - a concept that feels much less like a crime. He will not condone theft - but likely feels ambivalent about making unlawful copies of digital content. He may frown upon crude graffiti - but just chuckle at the sight of exploited persistent XSS on a popular website.
An argument can be made that the incentives in online interactions are so different from these in the physical realm, that any such comparisons are simply inappropriate. But then, consider Wikipedia - a design that stands against everything we know about information security, yet demonstrates remarkable resilience in the face of attacks.
Here's a perverse thought, then: what if our pursuit of perfection in information security stems from a fundamental misunderstanding of how human communities can emerge and flourish? We are essentially preaching a model of a society based on complete distrust - but as the complexity of the online world approaches that of real life, the odds of being able to design perfectly secure software are rapidly diminishing; and the impact of being so paranoid is already taking its toll on how much we can achieve today.
If this model is not sustainable, will our online world share the fate of many other early civilizations - collapsing under the weight of its own imperfections, and ultimately, going the way of the dinosaur?
Perhaps; if so - new, more enlightened communities will certainly emerge.