A lot of the times I believe this to be true yes. Even if they haven't come to learn of the pain they have inside. That said there are some people who cause pain because they just need to be right, and don't care lol.

Maybe, but that’s no excuse

Yes, but I guess alternative causes can be greed and ignorance, combined with a disproportionate amount of power.

I think most people have pain inside, but when they cause other people pain intentionally it's because they're phuque-os.

It seems to me that is often the case but though it might be an explanation it isn't an excuse.

No, but they will.

I believe there’s a lot of truth to this

That's no excuse to inflict pain on others. Who doesn't have pain inside anyway?

No.