because christmas is near so many investors will invest in bitcoin that is why bitcoin go up so fast. Let see what will happen when christmas day maybe it will dump the price because they are going to sell bitcoin to buy something or spend it for parties.
The main reason is the high price of the bitcoin and its high raising rate in the market, due to which a high number of the investor taking interest in bitcoin and making their investment in the bitcoin. the high rate of the investment make it to move fast. again when the rate of the bitcoin is raised the interest of the investor is raising. The high security is also a key feature of bitcoin that make it trusty due to which people make their invest in the bitcoin and thus the value of the bitcoin move fast.
Well that's what is asked, the question 'what makes Bitcoin move this fast' means, how can Bitcoin reach very high price in a very short time? So having a high value is not the main reason as you think it was.
But its true that when the value of Bitcoin increases so does the demand, that's pretty much the basic laws in economics, it applies even if it is a decentralized currency.
Having high security? The truth is, it will not provide any security at all, as it is merely just a digital currency. The ones that will provide you security is those wallets that you are using, but its mostly up to you as you are responsible for the security of you wallet alone.