Why are so many West Africans, notably Nigerians/Ghanaians scammers?

On Facebook, many of them create fake profiles, usually with a western sounding name and fake profile pics. A friend of mine was scammed off $550 by a Nigerian who was claiming that he would sell him a PS5. In South Africa they're known for drug peddling, trafficking children into prostitution, and are generally an unpleasant lot. Is this what they do all day in their country? What happened to honesty and integrity? Isn't this the reason their countries are corrupt, unlivable hell holes?