Killmonger' plan was stupid. If Thanos didn't exist (cuz even Wakanda couldn't do that alone, though they have the best chance) he should have been patient.
If he was really about it, I would have annexed some territory, slowly open up an expanded Wakanda to select black people worldwide. c00ns who possibly spy for another country like the states or Canada or a European country are executed.
If you have ever played a Civilization game then you'll know what I'm talking about. It's better to go for a cultural and scientific victory than conquest in this case. Once your tech is to the level that you are practically invincible then you can invade. Even then, I wouldn't go for conquest but instead remotely improve the stock of black people worldwide. If an unjust police shooting/brutality case occurs then there will be consequences, if outright discrimination occurs then consequences, racist comment to the media then consequences.
Bringing everyone to Wakanda is not a good idea, it will damage the culture that made it so successful in the first place. But allowing the diaspora to elevate their standard of living and education to greater heights is the better option.
Again, eventually, the fact you are so scientifically advanced and rich will allow you to become a world power or "rule" the world. In time.
Going around starting an unprepared war is stupid.