The crisis in Cyprus happened to be the initial catalyst for the big increase in the BTC price. After the country was bailed-out people rushed to their bank accounts to withdraw funds and a lot ended up putting the money into bitcoin. As for the incredibly high price by the end of 2013, the demand for BTC in China in november was so high that some prices quoted on Chinese exchanges were almost double compared to exchanges outside the country. The rest of the world has been buying bitcoins to try and sell them to Chinese. Don't fool yourself with this tax idea.