One can simultaneously believe something is neither worth buying nor shorting. In this case, Bitcoin’s volatility and meteoric rise make predicting the timing of its crash risky.
That doesn't mean you should short it. Bitcoin is casually up 6% today, in recent history it has had daily gains in excess of 20%. It can rise by multiple percent in a few minutes.
You would have to be completely nuts to short it, regardless of what you think it is going to do in the medium-term.