I'm taking exactly that into consideration–Nigeria has a sizable population, but very few people who can actually buy expensive consumer goods from western countries. So the odds are even more likely that orders are fraudulent. This isn't a country with a giant middle class.
Those few are actually in the order of hundreds of thousands if not millions. You are talking about a 173 million people country.
If only 1% of 173 million had a western-like middle-class+ purchasing power, that gives you? 1.73 million. A lot of people you can do business with. Like 4x that of Luxembourg.
You are also not taking into consideration that I, quite frankly, do not have the time or expertise to vet everyone who tries to buy something from me.