People who have been shorting this market have no doubt made a killing. Only the bounce from February was a worthwhile trade imo, the rest was garbage for long positions. Imagine if you traded longs in 2017 and shorts in 2018 though, you'd be rich by now! I would never short BTC, though I can understand why people do tbh.
Not sure if there is really a worthwhile trade but I get your point.
I haven't personally shorted Bitcoin or other cryptos this year, but I know for a fact traders have been making small fortunes this year. Whether it be from $12K, $10K, $7.8K or $6K, people have managed to double ot triple their fiat (or BTC holdings) by shorting on Bitmex and other exchanges. Not forgetting the epic BCH short from 0.1 BTC down to nearly 0.3 BTC, I know traders who doubled their money on this trade this month, or more if using leverage.
In summary, the gains people made last year when BTC went up 4x in value, people have made the same if not more by shorting BTC, BCH, ETH and others. Saying that shorting this year was pointless when BTC went from $20k to $4k, is like saying there was no worthwhile trade when BTC went from $4k to $20k
