Believe most times is either people that don't know about Bitcoin
Or in it for short term gain are ones that loss interest.
Exchange failures, security failure, site
breakdown, wrong source of information
None of these are Bitcoin
It doesn't use a site nor does it need an exchange and wrong source means you listening to content creators.
Some investors channels their money to real
estate, stocks, hospitality and other assets that
generate good income or bring good returns.
Ever heard of diversification?
Nothing is absolute
Stock price also fall.
Fear about hackers, scammers and fear of losing
Hackers and scammers have been existing way before Bitcoin was created.
Many people really need money for business,
Education purpose , including emergency needs this makes Long term Bitcoin investments less efficient.
This is why many are advised to invest from discretionary income.