If we look overall, I think BTC should be taxed. Although I know the tax amount is going to be deducted in our profit only but it should be taxed and the reason being is that it could only be taxed if government centralize BTC and thus all the illegal activities associated with BTC could be banned. As far as there is no governing body over BTC and everyone is using according to their work including terrorist so humanity comes first, before profit also, so there is no harm ni taxing of BTC.