Despite having the largest population of any country in sub-Saharan Africa, Nigeria has one of the slowest-growing economies of similarly sized countries, and in most areas average per capita income and life expectancy are actually lower than they were at independence in 1960. The country has extraordinarily low productive capacity and oil, narcotics, and financial scams are the three main generators of foreign currency. Oil accounts for 80% of budgetary revenues and as a result, high inflation has hurt investments for the average Nigerian and made international investment aside from oil an impossibility. The “Golden Decade” of the 1970’s oil boom led to massive spending and borrowing on the part of President Murtala Mohammed for grand-scale modernization projects that remain uncompleted. In the following decade the price of oil plummeted under the Babangida regime and even basic food stuffs become too expensive for consumers and Nigeria had to default on numerous debts. The economy has yet to recover to early 1970’s levels of prosperity and today, the majority of Nigerians live on less than $2 per day.
Take a look at the CIA World Factbook on the Nigerian Economy: https://www.cia.gov/library/publications/the-world-factbook/geos/ni.html