This is an interesting idea I saw about a year ago, some were skeptics, but looking at this again, I am curious if it would work, why or why not?
You could try simulating how a levered ETF would have performed over the past 50 years.. and try simulating the strategy you mention.. my guess is you'll find that you sometimes get blown out of the water, even though if you simulate the strategy over the period where the etfs existed you'd likely seem to be fine (which is probably why some people think it works).
it doesn't work because no one will lend you the leveraged etf to short try shorting one yourself if you don't believe me