I think it is not only a mental challenge but also it is an emotional challenge.  Many have the mind set of hodling but most of them give up on emotional challenges due to fear of lossing when Bitcoin plummets to a certain degree.  Also, we know that in an investment and trading, not only mental capability is important but also the emotional capability plays a significant role in how a trader maintant their composure in Hodling.

Many investors gave in to fear and became weak hand, selling their stash the moment the price of Bitcoin take a dip.  FUD will never be called FUD if it does not affect the emotion of a trader.