I don't know much about the Nigerian economy, but there are certain reasons and wrong economic policies that lead to such a continuous decline of the Nigerian naira against the US dollar.
I am not surprised because here in my country the same thing happens. The stupid and disgusting economic policies of the government lead to the continued deterioration of the national currency against the dollar. It has now reached 14,000 national currencies for $1 and the decline will not stop, of course.
Although, as far as I know, economic resources exist in Nigeria, I expect that the government's wrong economic policies, in addition to government corruption, are the reason.