Can you name three ways that proves people are stupid? (Answering my questions can't be one of them.)

Mormonism exists

Cigarettes are still being sold

Trump still has supporters

Maybe not examples of stupid, but careless for sure.

Some people leave their babies and pets in cars when it's hot outside.

Some people stay in abusive on again, off again relationships and get hurt over and over again.
I'm guilty of that one.

Some people hold fireworks in their hands as they go off.

Some people get married more than once.
Can someone please explain to me why you would do that?

I was just going to write "Donald Trump is president" three times but Don B. kinda ruined it for me. 

* Warning labels on appliances (On a hair dryer -  "Do not use while in shower")
* Cheating on a pregnancy test (someone forgot to study)
* Smartphones (need I say more?)