[roc]

It's that old line that the market can remain irrational longer than you can remain liquid.

In betting against a bubble, you're not placing a bet that the underlying assets are over-valued. You're placing a bet that something will pop the bubble in the timeframe you can afford. Essentially, you're not betting against the bubble, you're betting on the pin.

[omarkatzen]

With put options, you're betting on a timeframe. You make a profit if the price drops below a certain level by expiration.

With naked shorting, you're betting on it not getting above a certain level (the level at which you face margin calls you can't meet). It could go up 10x tomorrow and kill you.

[this_user]

Your description of 'naked shorting' isn't accurate. Options are derivatives based on an underlying (BTC in this case). Short selling is the process of borrowing the assets you would like to short (for a fee) from another party and selling the them effectively leaving you with a negative position. If you decide to cover your position or if the lender demands you return the loaned instruments, you will have to buy back the assets. This is the standard process of shorting and you will usually not wait to cover until you get a margin call from your broker, but do it if the trade doesn't work out. 'Naked' short selling is the same process, except you never borrow the assets in the first place. You effectively sell something that you don't have. This is possible if don't have to deliver the sold assets immediately, but it will eventually lead to a 'failure to deliver'. This practice is usually illegal and your broker won't let you engage in it.