Humans are constantly chasing down satisfaction. This grasping is the fundamental cause of all misery. Ok, so I'm getting a bit Buddhist philosophical here but if you think about it, it's true. Why do people do drugs? Because they want to feel good. But of course the high is impermanent, so they get pissed off at the world and go find something else to try to fill that void; and the cycle continues.

The truth of the matter is, yes we are our own worst enemy - but the solution is simple yet simultaneously not so simple. We have to learn to truly be happy where we are now. Break out of the cycle of blind reaction. Sadly this requires quite a lot of introspection which some people are just not ready nor willing to do!