Why did the price of bitcoin increase so dramatically?
some reasons for the price-increase:

-bitcoin becomes an official currency in japan

-Australia Will Recognize Bitcoin as Money and Protect Bitcoin Businesses, No Taxes

-many people know/buy bitcon now, who did not know bitcoin some months ago (in many countries) caused by increasing media coverage

-bitcoin becomes an alternative currency in venezuela, Nigeria and some other countries caused by internal political problems

-the scaling problem seems not to be finally solved but the segwit-activation could improve the scaling-situation

-Russia’s Parliament is Discussing the Legalization of Bitcoin

-meanwhile the blockchain-technology is more established: there are no known hacks of the blockchain self