Barely being able to contain violence should be concerning. It's one thing just to know you are capable of violence, it's entirely different if you are struggling to control it.

I think you misread op (either that or I did).

I didn't interpret the post as "I was feeling barely containable violence then" but more of a "I became aware of the barely contained violence that me/humans have under the surface". As in, a change of judgement on his current and past condition, rather than a new emotion.

LSD alone does not create any violence, it does not bring any evil into your mind from the outside.

It mostly shows things that usually stay in the unconscious part of our mind. It is more like a lens than a seed.

Of course Barely being able to contain violence is concerning, but let's face it, it is a daily struggle for a LOT of humans. Our good intentions dp not always weigh up when for example we are starving to death. Anger, greed or hatred, are some of our common struggles, but most of the time they stay hidden in our subconscious, bc we do not like to see ourselves as persons able to perpetrate violence.

But only when we see it (it requires honesty, not necessarily lsd xD) and we resolve to work on it, can we really grow.

OP said evil, not violence. The boundary between good and evil is so thin, that people cross it without even realizing that, e.g. when they wish or do something for personal gain. It's just most people have zero power over others. Evil is indeed barely contained in a typical human today.