Well, we know that bitcoin dying is not caused by forum posts announcing that it is dead, because we get those on a daily basis.

If everyone stops using it or if in some way becomes wothless, these are the two situations I think of that could make bitcoin die. But I don't know what could cause something like this, people get used to bitcoin and all benefits that it gives and demand is geting biger all the time.

There were already some cryptocurrencies (very small altcoins) that "died" - that means, the blockchain doesn't grow anymore because there are no users (=users with running full nodes). Example: TGCoin.

That would be the most probable scenario for a "dead Bitcoin", too. No demand, no users, no transactions. The "why" question would not be that relevant - it could be a better cryptocurrency or - a bit sci-fi - less need to use money for everyday life, or a much better technology than cryptos (e.g. a kind of artificial intelligence which manages our needs). It would not be dramatic, just boring - "the last Bitcoiner" will power off the light, most probably without anyone noticing it.

Another scenario would be a severe software bug. That could be much more dramatic, because it's very probable that there would be still people trying to use it. Although in this case if the bug can be solved, the blockchain can be started again, although there would be, for sure, a big price crash. This also already occured in some altcoins (e.g. Slimcoin).

Sme cases that came into my mind:
* something (quantum technology, mathematics) that make the cryptography behind Bitcoin obsolete/hackable
* humanity finding out that deflationary coins are bad (I doubt that)
* people deciding that Bitcoin is not anonymous enough for they use/need (this is not for all cryptos though)

Gold Finger Attack

Support from the community, if the community will stop using bitcoin at all then no sense now of it's existence. Bitcoin exchanges will now have a ghost volumes since no active traders at all, merchants that accepts bitcoin will remove bitcoin as one of their payment method, Bitcointalk forum will become a ghost forum and many more.

Good thing no such thing like that will happen to bitcoin so long live. Others alts already suffered that less support from the community resulting to a dying coin/s.

When the trust will fall. Which is never becuase is is anonymous. Thats my guess

Bitcoin will die if blockchain will stop to work,if miners will stop to work will be no confimation,what will be whan last block of 21 mln limit will be mined,like i knowthere is no solution in that case,but there is still time uhtill last block will be mined

Bitcoin would end up only, if all users will be gone away or disappear in this industry, and that will happen only if the features of bitcoin will no longer be implement and not function properly which might cause of the community be get disappointed unto it. which will lead the value goes down into zero.