Why Do Nigerian Women Love to Bleach Their Skin?

I recently saw some ladies in a gathering, the last time i saw them was over 5 years ago, they were black and beautiful in colour but when i saw them last i hardly recognised them because they have totally changed in colour, they now look very different that somebody had to be telling me they are the same people i used to know. They have bleached their skins. I realise this is a common thing in Nigerian society especially among the celebrities. Why do they love to remove the original skin God gave them? Can somebody tell me?