Nigerian Scammers?

why are most Nigerians scammers??? can't they make money the decent ways?? i received ALOT of mails from so called credit companies & bank managers from Nigeria claiming that they can give me good credit loans... after some upfront presentations, using religion as their platform eg.("I am a God fearing person") to try and convince me that they are genuine bankers, then they drop the bombshell....... they then ask me to PAY "certain amount" to receive the loan money.. which in this day and age.. any idiot will know that after you pay them.... they gonna disappear!!!! why can't these Nigerians find decent proper jobs to earn a living???!!! Are scamming all they are good at???!!!!!