And see; that’s the clincher.
The “scale” here, all things held equal, is minuscule.
21,000 people died during the Syrian Civil War last year. In total. That’s all the civilian deaths, all combatants, From ISIS, to al-Nusra, to the Syrian Government, to the Russians, to the Kurds, and NATO.
Now compare this to the fighting around the Pusan perimeter during the Korean war, where just as many people died inside a month.
It puts things into perspective. The Jihadis, in a failed state with all the manpower and weapons they can muster, with practical free rein to kill whomever they wish, still fail to measure up to casualties inflicted during skirmishes in the Forgotten War.
If I move up to World War numbers; the picture becomes even more stark. There were battles in WWI and II that killed ~21,000 people in a single day. A notable defeat to the British, the Battle of the Somme, killed well over twice that many, again, in a single day.
Even if ISIS managed to spread their operatives to more 1st world nations, even if they were committing something like the Paris Attacks every month; they’d still be behind by more than a factor of 20x to the casualties the World Wars caused to the people of Europe.
I don’t wish to undermine the threat ISIS presents, but we should be clear on what precisely that threat is. ISIS is a regional power that has successfully compelled sympathy and support from groups from around the world. They are very much like the Tamil Tigers, who, until ISIS arose, were the most deadly terrorist organization on record (even more than Al Qaeda.)
The power they wield however, is nothing like that of the Imperial Japanese, Nazi Germany or the German Reich. In conventional terms, they are very weak, not even strong enough to take on or defeat any of the Middle Eastern powers in a outright war, and nothing on the “Horizon” is set to change that.