I’m fairly certain it’s a bubble but it’d be foolish to short. Altcoins are in a bubble as well—Potcoin being valued at $64mil is just one of many examples of coins with zero or close to zero utility valued at absurd levels merely due to their visibility as a cryptocurrency (much like dot coms in 1999).

Ultimately, the mania present in a bubble can persist longer than one can stay liquid, i.e. Bitcoin could double or triple before the bubble bursts, which would trigger a margin call on a short position.

"The market can stay irrational longer than you can stay solvent." Calling the day when a bubble will pop is hard.

I agree folks should put up or shut up, but it can be both true that it will go to 100K and be a bubble. And if you short it now, you'll go broke even if it later crashes to 0.

There's not many places that offer options on Bitcoin and even less when you consider they need to be solvent enough you'll actually be able to cash them out.

One rationale would be that a person believes they cannot time the market correctly.

It takes another 15% spike and your short margin position pops just 10 seconds before it goes crashing down again... this is happening all day long.

I've been thinking about options as a way of doing that. But if anyone is selling put options on bitcoin, they're... probably not wise.