Well, no one can tell the authenticity of Op claim except him. Perhaps, presenting a paper documents for the purchase house with sensitive information strike out would serve as evidence to prove every doubters wrong.

Doing some comparison with Nigeria currency, that's roughly 14m and that amount can afford you a standard two bedroom flat in some locations especially in the north depending on the land size as well. The amount can not acquire you a plot of land in our major cities thou. Maybe Op bought the house in a remote area where things are less costly and probably furnished the house himself.

From the uploaded image, you can see it is not a mansion but a single roof house probably a two bedroom flat. Also, the amount above could exclude the furniture and other furnishings. I'm not trying to defend Op story but I'm analysing the possibility of his claim.