why bitcoin is still illegal in many countries of world

Is there any solid reason behind this ??/
Its because the government doesn't really support bitcoin and for that they really don't know what bitcoin is same here in my country i earn bitcoin alot but its illegal here and i just spend my bitcoin on steam and load its very sad..

i don't really think that in my country will accept bitcoin because they think that bitcoin has no value to them
Bitcoin has a value. However, in your case, it doesn't have a value only in your country, not in gobally. Hence, you can convert it into fiat any time you want giving it a value. If you want to convert it, just sell it to other people in other country like Nigeria, so that you can be able to convert it into dollar via paypal, neteller or etc. Sooner, it'll be accepted in all countries.