Many times people get rekt by this strategy as price does not come back in the bull market. This is not a good strategy to convert to USDT and then again buy bitcoin.
However, you can still wait and hope that bitcoin will dump to 14,000$ before crossing 20,000$.
This is not a bad strategy - at least he exited profitably. He doesn't have to go back to the market and feel like he missed out on profits.
A much more dangerous strategy is to buy a falling asset in order to average out your losses or buy an asset that has already grown strongly, in this case it is probably better to stay out of the market. I believe bitcoin will continue to rise, but the likelihood of a major pullback is also high.