In some countries, corruption is inborn. For example, in Nigeria, a child has become corrupt immediately he/she is born. Almost all aspect of the country is corrupt. We just blame our leaders for our corrupt society but parental role is highly needed to fight corruption in any country.
Your post deserves a merit, because you have said a truth that many people aren't ready to accept, if Nigeria is going to ever change for the better it should start from within, every home now have parents that leads their kid to do bad things all in the name of a bad country, the leaders are doing their own and so are the people too and when it's time to elect another leader we always forget that the new leader will come from the people too.
I don't know much about Nigeria but I can definitely tell you that it's true in my nation as well. Leaders are corrupt because people are corrupt as well and they want to see people like them leading the nation. They are corrupt from the moment they are born because their parents are corrupt, their friends grow to be corrupt, the places they shop from are corrupt, everywhere they go there is corruption so they think its part of the world and never see any better.
It means when it comes to voting and electing an official, corruption is not a problem to them because they think its how the world is. Turning that to better would take decades of decent politician fixing everything and punishing hard on corruption, but they wouldn't be able to get elected.