When he’s right he is right.
The thing is that having 10x the casualties tends to create more fighters.
Until it doesn’t. Case in point is that large empires exist. Greece has the 300 story, yet were part of Rome and The Ottomans. China has Tibet. US has native lands. I get your point but freedom fighters depend on sponsorship (Haiti bring an exception) and they do exhaust. Still my point is that super powers can be defeated, its just at a very high cost.
The issue is about endurance. Are you okay with losing the majority of battles and having x10 the casualties? Not to mention all the left over bombs and chemicals causing deformations long after. A philosopher once said everyone has a plan until you get punched in the face.
That gives a certain poetic irony given the put down of the south.