A lot of people do, and for powerful reasons – we are facing enormous challenges unprecedented in human history, from climate change and nuclear war to engineered pandemics and malicious artificial intelligence. A 2017 survey showed that nearly four in 10 Americans think that climate change alone has a good chance of triggering humanity's extinction. But we seem largely blind to the many profound reasons for hope – and it's not entirely our fault. Humans are wired with a "negativity bias" that triggers a stronger emotional response to bad news than good news – evident in the journalism maxim "if it bleeds, it leads". This loss-aversion behavior served a purpose in our evolutionary past, when information and resources were scarce, but in the age of endless information access, it can lead to pessimism, anxiety and a distorted vision of what humanity is capable of.