Sorry for taking so long to reply. I figured I'd like to take some time to figure out the proper reply, because this topic - of control, of our darker sides and of life satisfaction as a result - is an important one for me.

First of all, I'd like to establish that the way you propose people act insults every single person's ability to act on their own accord. You seem to put much more emphasis on the external pressures than they deserve and disregard the importance of decision in any action. Certainly, their effect on our mind is undeniable - it would be foolish to suggest otherwise - but it's not everything there is to acting, especially to acting in ways less desirable.

Secondly, the decision-making is important for acting in any way. Existentialism establishes that everything is a choice, even not making a choice. I find this idea empowering, because it reveals that, like many things we think of ourselves, our perceived inability to control our lives and ourselves is just that - a perception, a feeling. It implies that human beings are, indeed, very powerful, emotionally and mentally, and are capable of persevering through the worst adversities of life without bending or succumbing to the ill event. It's incredibly hard to survive the deepest pits of internal Hell, I grant you, but it's not impossible, either.

With that in mind, I'd like to refer to a concept I've mentioned earlier. You misunderstood it as the power dynamic between people in a society. What I referred to, instead, was the feeling of power - or, more specifically, the feeling of control over one's life and oneself. It is through lacking it that we feel like doing evil, however petty or big. If a person feels in control of their lives - that is, of the events and, more importantly, experiences that make said life - there's no need for them to commit any sort of crime because there's no need for establishing this control. It's through the collision of the ideals - "That's what I want to have" - and the reality in which we don't seem to even have a clear way of having it that evil motives arise; it's ego fighting back for being important once again as it was in the childhood. It is this power that we desire: to change the circumstances that don't satisfy us.

Naturally, this requires a healthily-broken ego (that is, ego that's been subjected to the reality of the fact that the person in question can't always have what they want or that gaining it would require more work than they're willing to put in) to work in a way that's beneficial for the person and for the society as a whole - otherwise, the ego would take over and desire to change everything and stay mad while things aren't being changed - but it's not impossible to acquire said feeling of control, which is what I propose the be the source of evils many people commit. Naturally, there are things beyond our control even in our minds - autists, for example, can't "train" their brain to be like a neurotypical person's, and mental disorders are mostly inaccessible from the inside - but for the mentally-healthy human beings, that's the way to go.