If you want insurance so you can simply change your mind because there is an attack where you are, or want to be, then the terrorists have won. Having insurance to mitigate your costs doesn't make you a winner. You are still choosing to run away from terrorism.
Seriously, and respectfully, if such a statistical improbability of a terrorist attack is of such concern to you, then I would suggest that you are not psychologically suited for such an adventure. There are far more less frightening things much more likely to happen to you when travelling as most experienced folk can tell you. You have to be ready for the unexpected. You can't prepare for it. And if you have a less than adequate command of the local language then your worries will be quintupled if anything does go wrong. There are plenty of locals happy to make an illiterate foreigner squirm in their boots as they fumble through a phrase book trying to explain that they don't understand the language - let alone when it comes to explaining what you actually want (or understanding what you've done wrong). Even though they understand English ......
