Ignoring threats, or paying them too much attention?

On the passive suggestion of Parapundit's Randall Parker, I'm reading The World Without Us, a book by Alan Weisman that attempts to describe the future following the abrupt extinction of homo sapiens. It immediately strikes me as disappointingly misanthropic and distractingly quasi-religious (what Half Sigma terms "Gaia worship"). The recurring criticisms I have with this approach--the idea that humans have somehow unfairly intruded onto evolution's domain rather than being a product of it, the exclusive focus on biodiversity at the expense of biomass, and the assertion that while human immigration from the third world into the West is grand, all other forms of immigration (human or otherwise) are inherently bad--are present. Sifting through that, though, the descriptions given about the influence of humans on ecosystems, from what becomes of the salt dumped onto roads by trucks during snowstorms to the fates of potentially feral pets, makes for intriguing reading.

My point is not to give a book review. I'm not even 100 pages in, and, more importantly, reviews are, uh, not a personal strength. I did, however, want to tap readers for thoughts on the following passage (p3), where Weisman asks whether or not humans will realize the point in time where they've crossed the rubicon, dooming the planet as we know it. Seems to me that he gets it exactly backwards:

The truth is, we don't know. Any conjecture gets muddled by our obstinate reluctance to accept that the worst might actually occur. We may be undermined by our survival instincts, honed over eons to help us deny, defy, or ignore catastrophic portents lest they paralyze us with fright.

To the contrary, are we not 'excessively' worried about all sorts of perceived threats that are, in reality, far less threatening than we imagine them to be? We're afraid to go swimming in the ocean for fear that we might be mistaken shark bait, even though the annual number of shark attacks in the US averages less than 20, and less than 5% of those are fatal. We scurry indoors during a thunderstorm, even though the chance of getting struck by lightning is infinitesimal. We have to fight through the sometimes numbing anxiety of approaching an attractive girl even though realistically the worst that happens is we're politely turned down. We buy home owner's and life insurance policies even though odds are we're going to lose money on the deals, because we fear the worst. We're disgusted by the idea of eating a piece of food that falls on the floor, even as our pets happily show us how silly that worry is. We regularly go through media cycles in which the next big pandemic set to ravage humanity is spotted, with hysterical documentaries close behind, before going out with a whimper ahead of the next big pandemic just over the horizon.

What are the real threats that we systematically tend to ignore? Catastrophic anthropogenic global warming, maybe? The fact that business owners will intentionally make economically poor hiring decisions and run their businesses into the ground just to spite a black guy or a lesbian, too, I guess. Uh huh.

From an evolutionary perspective, this makes perfect sense to me. Survival is the primary objective, more important even than reproduction, as the former is a prerequisite of the latter. Better safe than sorry. That veritable aphorism is one that Weisman, as an author, surely benefits from.