Don't tell anyone that Bitcoin is going to give you profit without any risk. There are many people who were told so, later they panic when Bitcoin price starts to decline a bit. In the end, they sell their BTC because they are afraid of loss. It's been almost 4 months since correction started and it looks like we are far from recovering. Even though Bitcoin is decentralized, tax still can be applied. It all depends on where you sell your bitcoins. If you use an exchange and cash out to your bank account then you won't have any other choice, they will eventually come after you.