An aunt once told me: "People are assholes and have to prove the contrary before you can trust them".

I guess I fared great with the opposite approach. Almost all people are good.

(Yes, there are psychopaths and they are dangerous. Don't give all your stuff to anonymous strangers but trusting a stranger with a bit of money as long as he'll stay in fist's reach until he probably will prove his trustworthiness is totally fine.)