What are the caveats on selling a SSF on, say, FAZ, instead of shorting or buying a put. I assume the price has the time premium or hard to barrow % built in. And yes, there is the spread. But with FAZ, it seems like an almost no-brainer. YEs, long-tail risk, but that can be hedged, still leaving an instrument that is built to decline and generally does in the intermediate-long term. What am I missing?