I will not say unstoppable. But Bitcoin is really performing well now stable in it's high price that was reached for the past 5 years. But someday, if some negative big factor will come, it will really bring down the price.
the closest is the upcoming fork, I think the bitcoin price will decrease a little because people tried to buy the bitcoin to receive BTG and at which they will sell the bitcoin. It seems like people buying up BTC to get as much Bitcoin Gold from the upcoming fork is playing a huge part in the price increase. However it will reduce slightly and then back to strong growth. $7000 at the end of the year is feasible
Upcoming fork can't hurt bitcoin, last time people were afraid and in panic they were dumping bitcoins, now situation is different people are buying more and more bitcoins to have more bitcoin gold coins after hard fork. After hard fork people will dump gold tokens but bitcoin will continue to rise.
Bitcoin now is much more stronger then before, we can say its unstoppable but bitcoin is still young and needs to grow more and be more stronger as it grows.
Bitcoin value now is fall down so I think for now it is stoppable, but I know that after this coming hard fork bitcoin value were become increasing again. But it is not surely true, this is only my speculation and I hope that it will happen. However if the bitcoin value were not yet recovered I have second plan on what should I do to my bitcoin, maybe I invest it into different sites or still holding my bitcoin in my wallet.