As popular as it is to trade cryptocurrency, it seems it’s even more popular to hide it from the government. The American tax deadline is nigh, so U.S. citizens are tabulating their finances for Uncle Sam to take his cut. But a survey of 250,000 people filing their taxes on a platform called Credit Karma reveals that only 100 of them are declaring capital gains income from their cryptocurrency holdings. It’s a safe assumption that most traders aren’t reporting jack squat. Bitcoin tredecupled in value (that is, it climbed in value more than 13 times) last year, helping to turn cryptocurrency at large into a $500 billion sector. Thomas Lee,…