many predictions say this, I personally still doubt if BTC touches 1000000 USD hehe, even though that is not impossible.
but surely cryptocurrency will always go up.
and for bullrun at the end of 2018 everything is still a question whether it is true or not, if that is true then now is the right time to hold, and if it is not true, selling coins is the best thing and buying coins is potentially like btc and eth