Ultra-short ETFs

Ultra-short etefs have been successfully traded lately — volatility is off the charts, fly back and forth. I remember that it was similar in 2008 year at the beginning of the bear market — then I missed these deals because I did not dare to short, then I gnawed my elbows when I looked at the tests what would have happened if I had not missed. This time, it seems good luck so far.
Here is one example: