What is Bitcoin? What does it mean to be secure? And then how much more is really secure?
My bitcoins are spread out (by which I mean my private keys are not all kept in one place) helping make them more secure, i.e. no one breach would get all of my bitcoins. Btw, this is inconvenient for my beneficiaries.
Bitcoin (as opposed to my bitcoins) might be breached and then we could all lose all of our bitcoins at once. What could be the nature of this breach? One of those nasty 51% attacks? A flaw in SHA256, etc.
What about economical problems? For example, if Satoshi returns.