Why? Because you are a stupid primate!
We all are. Some less than others, but many, if not most, issues of human consequence resolve to this simple equation: human primate = not very bright. Perhaps the best example is the current debate suggesting, basically, that we are NOT stupid primates. Only a stupid primate could arrive at that conclusion based on the overwhelming evidence available to suggest that in fact we . . . . are.
Now, you might suggest "hey, we invented spaceships, computers, and toasters - you call that NOTHING!?" That's something for sure - but more a legacy of the fact we have a sense of history and a feel for technology than because we are really, really different from, say, a mountain gorilla.
To get a sense of how we'd live without shiny tech history, just check out the lives of aboriginal folks in Borneo or South America. They live pretty much like the rest of us would live but for our "developed world" history of lots of shiny things like cell phones and cars. But more important than shiny things is our tendency to carry on as if thousands of years of observing the world and people around us were for naught.
I'm not a doomsayer and think things are slowly improving in the world, largely thanks to clever innovations in shiny technology, but I'm really frustrated by our inability to solve - or even think much about - the serious problems that face most of our fellow stupid primates ....
...Whoa! Gilligan Island reruns are on - gotta go...