I think the idea with the "Nigerian" scams is to take advantage of the fact that the people they are trying for know bugger all about Nigeria, but have some idea that there's lots of shady money going around in the hands of people who are a bit naive and exploitable - that's why they are written in that way.

Like a lot of con-tricks the idea is to trick someone into thinking they can get rich by taking advantage of a sucker. Generally speaking you only get conned when you are trying to con other people.