Off course can bitcoins disappear becuase lots of peopel dont even know how to deal with the bitcoin and when you are only holding the bitcoins you are not able to deal
with the bitcijun and pleas drop them.,
Bitcoin wont just disappear just because some of the people does not know how to deal with it because the majority of bitcoin users are well aware of what is going on in the community or if what they are supposed to do with their coins, so majority has the authority, it wont disappear because of that reason at all.