I can't track CFD via my charts so I will stick with tracking GBTC. I think your payoff on your short will get you so excited that you will forget to scream >>> "Buy the pullback!" as BTC trades sub $3500. For those who don't trade and just HODL. If you do actually HODL til you lose 50% from your buy at $4000+...here is a blog where you can voice your feelings about how long you would HODL in oreder to get even on your last buy.
https://steemit.com/hodl/@joejustjoe/meaning-of-hodl-on-7-30-17
Just store that link in case you need it...gulp! :O >>> :-)