I believe that they are some people that follow this advice you have given and many of them have made some serious money from the market.  It is a good strategy to short when you know that the market is really going down.  Most of those that learn how to hedge when bitcoin was high and there was believed and evidence that bitcoin is going to fall through out 2018 have made Alot of money from the market.  Remember that what you know is what put money into your pocket.