Bitcoin itself can be brought down by another coin that offers better technology, faster transactions, more security, and ultimately a great "steve jobs" to sell it to the people.

Nobody would have thought back in the 80s and 90s that Sears was gonna go broke, or in the early millenia when myspace ruled social media and now is non existent. Think of Amazon today... do you see it in Sears' shoes any time in the future? It inconceivable.

I'll tell you this though, quantum computers become mainstream and bitcoin's security would be as good as showing your private key on live television.

I totally agree with the trust issue thing about bitcoin that if it falter the security issue,many people will give up bitcoin and could destruct bitcoin in the society. On the other hand,if there's a way for a stronger security system this won't happen. People are the ones bringing up the fame and also people also can bring it weaker if they won't do any action for this. That's why trust is very important when you commit such a thing with bitcoin. Through this,people help each other and will always will.

I don't believe the catastrophes you mention are easy to happen in near future. Bitcoin will be indestructible for many years.

I do not expect it to happen and do not want to imagine it because so many people have benefited so do not think like that

I think, the only thing which can destroy Bitcoin within a few hours is the loss of trust of all the bitcoin users into Bitcoin because of any bad reasons. Because I think regulations, bans, new type of cryptocoins cannot kill bitcoin. But if losing the trust of bitcoin users because of some security issues in bitcoin, this could make the bitcoin value fall very fast.

Government, People, Hackers and much more. Because governments have the ability to stop any activity that they think has a bad effect on their country. And if all countries are united to terminate the bitcoins it will definitely be the end. They are the ones who do the same as those who can break, With the wrong work. Hackers know that it is capable of steal any files, data or any computer content

Government are certainly the largest risk to bitcoins future. As others have said though, destroying it is next to impossible. it will just be push underground and used for illicit purposes. There is no mechanism currently available that would 'destroy' it per say. They certainly can regulate and pass legislation that makes it difficult for main stream population to use it, and that will just cap the value of it moving forward.

For me there are 2 ways how to destroy bitcoin. Its my opinion only (Y)
1. The Creator itself can destroy bitcoin since he/she created bitcoin, he/she has the power to destroy it too anytime heshe wants.
2. Bitcoin will be destroy if the internet connection in the world is gone. Thing that will never happen

You can destroy bitcoin.
It is easy:
Buy so much bitcoin you can buy.
Send them in you private wallet you have not saved...
burn your computer...bitcoin will be destroyed for ever with your computer.

Who can destroy Bitcoin ? they can't destroy bitcoin but they can stop  its value into the market if many countries will banned or not allowing bitcoin in their respective country through that the value price of the bitcoin will fall.