His cause was bigger than anything else. He was talking freedom for black people worldwide. fukk anyone who got in the way. I don't agree with him killing his girl but I understand why he did what he did.
I agree with the message itself, and perhaps some part of Killmonger really did believe that, but for the most part I just interpret all of that as a front for his own selfish goals. He was legitimately not a good person; the way some people rationalize and condone some of his heinous actions, despite his message, is the exact reason how literal dictators had came into power.
Erik didn't hesitate to kill his "allies", the followers that believed in him, the people he was supposed to be "liberating" in Wakanda, and would've likely damned even more black people (including the rest of the world) if he had succeeded. He was an emotionally violate sociopath that wouldn't hesitate to kill any of you for the slightest disagreement. How any of that qualifies as traits of a "leader" to some here is beyond me.