Perhaps the 10 for brevity because you can just shoot them in the head and be done with it. But it's not like killing regular ants is hard even if there's a million of them. There's like a thousand different things to spray on them. So, it really doesn't matter in the end.
Honestly, I think I would lose either way, just from the size of the ants versus the fact that they could suffocate me if there were a million of them. So I would probably say a million because because it would be a less scary way to go than being attacked by humans.