You've probably heard scientists speculate that the most crucial point in the development of an intelligent society, universally speaking, is just after they learn to split the atom. They gather that a great many of them learn to release great amounts of energy before they learn how to properly control it and hedge against disaster. This would lead to the extinction of such societies.
I think there's another crucial point, that has nothing to do with atom splitting, that occurs before then. One that we've already crossed. The more communal a society becomes, the less "survival of the fittest" goes on. After all, we'd be pretty cold-hearted beasts if we allowed people to suffer and/or die, if we could prevent it. But it goes beyond just keeping people alive. We lower the bar in education, to make it more fair. We insist on equal opportunity for all, regardless of ability. We attempt to "level the playing field" economically by taking from the rich and giving to the poor. We elect people to high office based on how nice they are and what logo they sport, rather than any kind of competence for the job they seek. Fierce competition is frowned upon because it makes the losers feel bad. Striving for excellence has been replaced with striving for order and mere survival.
There are already signs that this has lead to the dumbing down of the population as a whole. We accept as fact, just about anything the media's favorite go-to experts put in front of us. We have the ability to transfer thousands of generations of knowledge to and fro at a moments notice, but we're too busy watching cat videos to be bothered. We actually believe that spending more than twice what the government takes in and borrowing 8 times revenue, will lead to a robust economy. It must be true. The experts told us so. We take steps to make our most common energy source more expensive because it's leading to catastrophic global warming, as the average global temperature drops. We stuff ourselves with carbs because the food pyramid says to, while we scratch our heads at the "obesity epidemic" and the increased rates of cancer, diabetes, and heart disease. We see images, provided by Hubble, of what look to be galactic offspring of larger, older galaxies, but the differing "red shift" tells us that they must be billions of light-years apart. Who you gonna believe? The theory or your own lying eyes?
As we continue to accommodate the lowest common denominator, the species will get increasingly stupid. This may well result in our own self-destruction due to nuclear annihilation, but it wont be because we knew too much.