Short positions on highly volatile (and probably manipulated) markets are extremely vulnerable to short squeezes. There's no good way to take out a leveraged short that's guaranteed to remain in place for, say, six months.
Good to know, but just because any particular short position is not guaranteed to remain in place for six months doesn't mean there is no good way to profit from shorting Bitcoin.
The problem is that a leveraged short position that is closed out/margin called can lose more money than you initially invested. The market can remain irrational longer than you can remain solvent.