Mistrusting people is a horrible way to live. It leads to getting lonely and isolated. It's hard enough to accomplish enterprising and creative works in the world, it's hard enough to raise a great family, it's hard enough to make a positive impact on the world around you and have things run ab it better. Trying to do so without trusting anyone you meet is no good.
On the other hand, highly trusting souls who look to do significant things frequently find they've misplaced that trust. A majority of people are well-meaning, but details get fudged, enthusiasm fades, memory is poor, interpretations are different, judgments get clouded, and external circumstances intervene.
Hence, the counsel of the humorist Finley Peter Dunne --
"Trust everyone, but cut the cards."
It's an entirely solid policy -- give everyone large degrees of trust and goodwill, but don't put them in a position where they'd be tempted or benefit from doing wrong. Don't hand off mission critical tasks to people who aren't vetted; don't bet on people if you can't afford to lose those bets and haven't gone to war with them before.