Not to mention that if the number is particularly large, even if you aren't facing kidnapping for ransom or similar situations, loose lips could incline some bastard to rat you out to the IRS just to screw with you. Even if you are honest on your taxes and pay what you think is appropriate, what is the proper metric for taxes for BTC that appreciate in value? Do you owe the taxes at the time you convert to fiat or at the time you earn it? Are they short-term capital gains taxes or something else?
I'm no accountant, but I believe the rules on this (in the U.S.) are quite clear. When you sell your bitcoin for fiat, that's the taxable event. At that point, you need to specify a cost basis and determine your income. short or long term depends on how long you've held the coin.