Because Bitcoin and Blockchain are so related, even if Bitcoin somehow goes so down in its value, Blockchain will somehow bring it back.
Why?
Because they are correlated. One can not work without the other, not in 2018 or in the future. These are times when the revolution in economic system happens and due to that, Blockchain will always be alive just as Bitcoin will always be alive.

BUT...!

We must understand that there are certain differences.
Bitcoin is a currency, and Blockchain is a " platform ", something that changed the whole ball game.
One must truly understand both and then, only then will know what is what.
My point is that Blockchain is used for tons and tons of things these days and we will only see in the future the merits and use of it in our everyday lives when on the other hand, Bitcoin is still and will always be a cryptocurrency.