There are people that are actually good with shorting the market and it work very well them but here is something you need to understand about the market, time is everything you need to open a position in the market, when we are in the bull run, there are more opportunities of long position for market to go up more often than for it to go down and most of the times it quickly retrace anytime the market dump but there is risk as well.

Likewise it's healthy to short a market during a beer run, this is when you tend to make more money and it has it own risk, if you don't have liquidation price far from your mark price, you will lose money quickly because there are times we do have market squeeze when beers and bulls tend to liquidate each other account and it's the exchange that enjoys the fees been burnt for this operations.