A bubble market will abuse you as a bear-theorist endlessly. This bubble will likely not resolve in any desirable time frame (36 months).
This stock could easily double again (see DECK, GMCR, CMG, PCLN, AMZN...)
Bearish options against a fedflationary market are worthless. You cannot call the time frame of when the TLT will collapse because it is intentionally being held out of reach by the Fed. You are forced to call time frames or topping price levels that can easily be blown away (see ACAT, CRUS, STX).
Besides an overall downward market, what possible catalysts-to-reality will dump a stock like LNKD? Nothing. If it got to $150 on nothing, then no rational catalyst can bring it down. The only catalyst that kills these stocks is massive post-speculative selling (see NFLX, CMG sorta) that develops at an unpredictable time, and an overall market crash, which isnt going to happen soon.
Bearish calls on the bubble are therefore extremely ill advised. An "eventually it will implode" thesis is not going to be sufficient as you do not have an unlimited amount of time or margin to wait for this eventuality.
Now that there are no negative catalysts for the overall market, this 1505 level is when it becomes extremely dangerous. The risk of a crash is very high, but every dip is bought, so you wont be able to tell when it is forming up. Shorting on down moves or days doesn't work because the stocks bounce right back.
Ironically, more money is moving into the market now, when it is dramatically overpriced, than was coming in at SnP 1000 because that point the extent of the juice was still unclear.
Now, the juice is likely perpetual; no series of events or developments will cause easing to end in the near term.
Therefore, by fighting a bubble stock you are fighting the fed.