I think The psychological panic is the biggest threat along with the lack of understanding and trust that makes it easy for many newcomers to receive bitter fruits and losses. Some have misinterpreted the market to make easy and quick money realized - Rekt for them.
fomo, indeed this is the most often fatal mistake for newbies. Moreover, many news portals broadcast the increase in bitcoin many times, so they join without any preparation, in the hope that they will soon get a lot of increase as well. some are lucky, and some are not. turned out to buy at the peak, and then the price continued to fall. even though it was their own fault, but many later said btc was a scam and bubble.
knowledge is the basic thing to have in order to survive and make a profit here. if not having much luck then we should at least have a lot of knowledge.