Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. Albert Einstein
Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity. Martin Luther King, Jr.
We are in danger of destroying ourselves by our greed and stupidity. We cannot remain looking inwards at ourselves on a small and increasingly polluted and overcrowded planet. Stephen Hawking
The difference between stupidity and genius is that genius has its limits. Albert Einstein
Anyway, no drug, not even alcohol, causes the fundamental ills of society. If we're looking for the source of our troubles, we shouldn't test people for drugs, we should test them for stupidity, ignorance, greed and love of power. P. J. O'Rourke