I think the fair comparison is to 1935-6. Nazis already showed what they want, but no large scale blood-letting yet. Spain is bleeding, but its mostly reds v browns, so who cares. Bolsheviks won the very bloody Civil War in 1922 and after some years of relative quite exterminated productive farmers as class and further subjugated Ukraine with the famine. But it was "far away" so the west is still full of utopian communist sympathizers. Japan is rising, but their demands for more resources are understandable, aren't they?
We are not in 1942 yet, and that's the point: this way around we can avoid it.
That would make more sense, but I still don't know about his comparison. If Hitler had started blowing things up in the twenties, rather than take over Germany, he wouldn't have been as successful as he was.
Of course there are differences between European and Near Eastern cultures. Perhaps terrorism is more attractive to some populations than to others, but controling a nation and its resources usually makes a maniac far more formidable than just calling for terrorist attacks.
You can see this by contrasting Lenin with his precursors who robbed banks and killed officials. I'm sure that today, such terrorists would be more formidable with the weapons that are available. But it's debatable whether they'd be as much of a threat as a present-day Hitler or Lenin in command of a nation of many millions would be.
Now it may be that the danger now is that you can't precisely tell where the threat is coming from. You don't have a large nation that you can point to and say, that is the enemy. And the process of deterrence doesn't work under those circumstances.
That may very well make things worse, but it also limits our ability to cope with the situation. Do everything right now, and you may still be hit with a strike from abroad.