I think this isn't something you can answer without context. I don't believe it's in human nature to antagonize others or self-sabotage, it's the world around us that pushes us to do so. On a systemic level, I could say the world is inhabited by a significant amount of people who work towards my demise (misogynists, homophobes, the conservatives and the right wing in general, etc.) It wouldn't be crazy to say that those are my enemies. That is because my position in the world has a direct effect on my relationships with others, whether I like it or not.

And it also has an effect on my relationship with myself: is insecurity in my nature or does it stem from past trauma that has shaped the way I interact with the world and continues to hinder my progress in life? I believe it's the latter. Meaning the only reason I can become my own enemy is because I've been somehow taught to do so.

In a way, all of that is a (direct or indirect) consequence of the circumstances that surround us, the context we grew up in and the experiences that made us who we are today. Does that mean that the real enemy is the world itself? Well. I don't know if I'd go as far as to say that, but the world can be a very hostile place sometimes. I guess those are my thoughts on the matter, if it makes sense.