Its an airport and we've got departures in both international and local flights in which, the flux of people goes both ways (arriving as well as boarding to leave). That goes for the image so its not like, everyone is just running away to other nations.
Again, I would say it's not abnormal for citizens from under developed and developing nations to seek green pastures over seas or in some developed nation. Its normal for people to want to do that and even take vacations.
In a nation like Nigeria where most things are far from perfect, I wouldn't expect anything less of the citizens that can afford to spoil themselves or those who see a feature outside of the country.
What I would say is, they shouldn't forget to develop home. Your always going to be a foreigner in another man's land no matter how you acclimatise.