"destined to fail"
I'd love to believe that evil would just go away if we ignored it. That Hitler, or perhaps Stalin, (whoever came out on top of the charnel heap) would have faded out in a few years after eating Europe and the rest. It would make life a lot easier, wouldn't it?
If you think tyrannical conquests are unstable, you might want to look a bit more closely at history. From our perspective, it might be hard to realize that empires that lasted centuries were not exactly short-term aberrations.
Al Qaeda declared formal war on us, in writing, in 1996. Nobody cared.