Once upon a time a boy didn't covered his trades and lost all his crypto holding to the Bitmex liquidation engine haha
What scares me the most is governments making a common front in banning Bitcoin and cryptocurrency. That would slow down the BTC price growth, but it will still continue to exist in the "underworld" of our society. However by the nature of the technology Bitcoin cannot be literally banned. I'm sure that people would still use and find ways to do so, but the adoption rate would be very low but it would crawl until governments will be forced to lift the ban. That's my view on my fear, so it is not really a fear but a wish that doesn't happen.