Dumbassness, ignorance is bliss, the state of being stupid and not thinking about other people or things that are dangerous, potentially deadly or embarrassing and sometimes illegal. Humans are prone to stupidity that's in their brains. Some Humans don't even have their mines straight, therefore, they can't think before they do something.
The stupidity from natural consequences and also people and animals doing stupid things because they are bored or just plain dumb. Like birds smashing against the glass of the doors thinking it's an opening however that is their own nature. Natural stupidity in humans dates back to the dawn of man when he was stoned out of his mind during the Stoner Age.
Some humans are naturally stupid and it's not their fault however it is their fault to act upon their instincts if you can call them that because there are two types of choice receptors the "don't do it you're going to die" and "do it we all die sometimes" signals that go to our brain. These signals or intercepted by smoking too much or drinking way past the limit of alcohol. Also eating florb and sniffing fecal oil can and will result in stupidity.