Stops are good... USUALLY. In Bitcoin, they can be very dangerous. Mostly due to order depth being too shallow. If you set a stop right now, a large enough sell would blow through it and your stop would sell you out at the bottom and you'd be looking in disbelief as the price heads higher without you. This happens in both directions, obviously. It's safer to decide an absolute mental stop, set an alarm on your phone when the price is hit and assess the situation before exiting. When the price spikes against you, you can almost always get a better price than what you see at the time of sell-off.