I ran across this video a while ago on what can happen to you if you don't pay your taxes. At some point during your Bitcoin career, the cryptocoin will be converted to fiat and that's how they will catch you.
https://www.youtube.com/watch?v=hf2fNEUPjQwwhy sould you evade taxation in the first place? It where government projects and developments get their funds from. Aside from it's your obligation, the benefit of it returns to you. So unless you don't trust or badly hate your government you should pay your taxes.
You don't wanna grow old knowing that funds alloted for your retirement goes to zero right?