Why are Nigerians who go abroad so successful while Nigeria is such a mess?

Just a simple question, worth asking I think. Nigerians are amongst the most successful diaspora in the world; in the USA, the UK and pretty much everywhere. So why is Nigeria itself such a mess?

It’s an important question. Black people in the US suffer, on average, from the generational effects of slavery to white people. Nigerians, some of whose ancestors may have done the selling, don’t. Maybe that’s all that’s in play. Maybe the folk luckiest in the genetic lottery simply see more scope to exploit their talents abroad, on average, while those who aren’t stay at home — again on average? And they land in places where they have the advantage over black people whose ancestors were kidnapped?

Either way, Nigeria seems like a nation sustained only by the fact that it was told it was a nation by its imperialist overlords? And now by the interests of the US and, marginally, the UK?

It seems a bad look, whichever way it falls.