Trusting people is healthy. Trusting everybody is just leaving your car unlocked in a busy lot.

Openness and indiscriminate openness are not the same posture. Extending trust is how anything worthwhile gets built, and extending it to everyone equally is not generosity, it is a failure to notice that people differ. Judgment is not cynicism; it is what lets you keep being open without getting flattened.

Give trust in increments and watch what comes back before you give more. Pay attention to how someone treats people who cannot do anything for them, which is the cheapest reliable signal available. Stay open by default, and save the full version for people who have shown you something.