Why it is that Bitcoin is not accepted in our country (Nigeria)?
WHat do you mean by not accepted? Is it not accepted by the merchants or has been blocked by the government? If it is about the merchants, then chill! That is not available in most of the countries so the people are using it as an investment asset instead of purchasing currency. However, if it is by the government, then you have to understand that your government don't want their people to stand financially.
Even in my country, the legal status of bitcoin is not clear. The government never issued any notice to the users nor legalized it. So I am mainly using it as a trading tool and as an investment asset. Whatever I cash out through out the years, I always include it in to my tax filing just to be safe.
The countries that have bad policies about bitcoin are inviting people to get their wealth in bitcoin and move it into another country that has more friendlier policies about it. For example if in your country the tax process is nothing but hell when it comes to bitcoin, and you risk getting your bank account frozen forever as soon as you get your coins sold and into your bank account, people will just move their BTC to another country and their country will lose all these potential taxes, so it's on every country's benefit to be friendly to bitcoin users when thy try to sell them, instead of making the process a mess and losing all that revenue.