Many have been betrayed and cheated by the people they trusted. But the law of sowing and reaping will always apply to cheaters sooner or later.
Meanwhile it would be good to heed this sagely advice:
Frank Crane says:
“You may be deceived if you trust too much, but you will live in torment if you don’t trust enough.”
Learn from the experience but do not abandon trust.
Here is my take on this: Trust in God but lock your doors.