Other crypt currencies are also rocketing.
One of the reasons is that "segwit," a new scheme for solution of the scalability issue, was going to be equipped in some currencies. This topic had been discussed for these some years.
Also, instability of political situation in some nations may be influential to the value of crypt currency.
However, I am doubtful to justify the current price of crypt currencies. The structure around Bitcoin is still vulnelable. In the near future, the prices will be damaged by some trust risks, I guess.