the simple solution would be to just cut Nigeria off from the Internet, they are without a doubt the source of most of these scams.
That is true, but it is truer to say that Nigerians, rather than Nigeria, are the source of most of these scams. Many of them are outside Nigeria and seem to operate with impunity despite occasional crackdowns. Nor do Nigerians have an exclusivity on this type of crime.
Cutting Nigeria off from the internet would penalise the huge majority of Nigerians who are decent honest people. It is sad that the actions of a criminal minority, which admittedly is a lot of people, have blackened
(oops!) the name of that country.
Educating people is the only realistic solution.