On the one hand, I'm sympathetic to concerns about insulting a large group of people. On the other, "Nigerian scam" is an extremely common way to refer to this, and is more specific than "advance-fee scam" which covers a class of similar scams. I don't think the name "Nigerian scam" is good but it is the name many people know.

Also, there's no citation for the "primarily in the United States, the United Kingdom and Nigeria..." claim. The reference to Encyclopedia Britannica is dead and presumably was for the "419" name since that's the sentence it's actually on.

I'm not sure what you're suggesting or whom you are addressing.

AFAIK, the reason the country of Nigeria is frequently associated with advance fee scam probably has more to do with a particularly famous example of a scam phishing email, where the email writer claims to be a Nigerian prince cut off from his substantial family fortune due to political issues of some kind.