Actually noone can destroy Bitcoin for now except the investors, if they're not paying their intension for Bitcoin any more, i'm sure Bitcoin will be dead.
Probably your ideas are correct. But there are also some instances that the people can destroy bitcoin especially those people who are good in programming. They can have the ability to hack all the bitcoin accounts and even our bitcoin wallet because they are studying how to hack. But maybe my imaginations are too broad about it. Investors also could be the reason that the bitcoin will be destroyed because if they will not pay what they owe and buy some bitcoin, so there is also a possibility that it will be destroyed because of them.