I believe that John Milius had it partially right when he wrote, in his script for Conan the Barbarian:
"Conan's Father: For no one - no one in this world can you trust. Not men, not women, not beasts. This you can trust. [Points to sword] "
You have to learn at an early age that you are alone in the world, and that you should keep your money safe. But you can't even trust yourself; you might be drunk, or wrong, and in the long run your body will grow old and feeble and will betray you, and eventually it will kill you after making your feeble and senile. You can't trust your own mind.
You should never entrust anything you hold dear to another person, and you should always watch your back. I cannot give you a positive lesson because there aren't any. Things do not happen for a reason; there is no guiding intelligence to the universe; you will never see your dead parents again; creation was not created; and the universe is a big electromagnetic bubble that is gradually winding down.