People don’t trust you until you trust them. I’ve heard the old used car dealer quip that "buyers are liars" and I know what kind of trust most people have in those same dealers.
One time in ten, trusting someone comes back and bites me. The other nine times, trusting people and achieving their reciprocal trust, pays back huge dividends.
I can accept failing one time out of ten!
Besides, it’s just less stressful trusting people than playing Chicken Little and being a skeptic.