Price volatility. The value of cryptocurrencies may change significantly even in a single day, which would mean a capital loss of your investment.
In December 2017, the price of bitcoin fell by 26 percent. If you had bought a bitcoin on December 19, 2017, you would have paid $18,936 for each coin. But if you wanted to sell it on December 23, buyers on the market were not willing to pay more than $14,048 - a loss of $4,888 for each coin.
In January 2018, the value dropped again by more than 10 percent, reaching the $8,000 mark. In February, the price fell below $8,000 and was traded as low as $7,574.20.