Vanguard won't allow you to purchase 3x leveraged ETFs, so this might be more difficult than you expect.
You agree the market mostly moves upwards, right? So if you go against the market, you need to consider when you go against it, and when you get back in. The shorter the time frame, and stronger your data, the better.
I carefully watched the Wuhan virus spread in China, as cases grew +50% per day. Yet the media wasn't doing any predicting, which is annoying. So I predicted 10,000 cases and a panic several days in advance, and that's what happened. I've watched Italy and South Korea fail to contain the virus, and now Italy is resorting to a lock down of the entire country (no longer just the North). Once the virus takes hold, it spreads rather widely.
The U.S. is behind on test kit production, and way behind on using test kits. During a similar period of denial in China, when enough test kits were available, the cases grew +50% per day. So I predict a very fast growth in cases, and reaching 10,000 cases in the U.S. in the next few weeks.
So what I did was sell 7% of my equities and buy mostly bonds. I don't pay the expense ratio of a 3x inverse ETF, and I get to hold bonds at a time I think stocks will drop. There's a better than even chance bonds will rise when stocks drop, which could mean an additional gain when I sell. Overall, selling your own equities is probably better than buying an inverse ETF.
But make sure you're doing it based on data, and with a narrow window for it to go wrong.
