GW has always taken a "It Just Works" approach to population numbers. I remember hearing that the Drucchi canonically always have Exactly as Much Population as they need to stay relevant, despite, you know, constantly losing thousands of soldiers to failed conquests of ulthuan.
It's also supposedly the same in the opposite direction. Losing a dozen High Elves is a super horrific tragedy, because, after all, they're always just barely on the brink of total collapse. Centuries to thousands of years of knowledge, experience, expertise, heroism, snuffed out by such a brutal world....
You know, like that time they lost hundreds to that Chaos Invasion, but don't collapse yet, because they're just barely on the brink of total collapse.
But it's okay, they can lose thousands in this huge campaign but not fall apart, because they're still JUST. ON. THE. BRINK.
GW either inflated or deflated the actual number of High Elves to always, no matter what, make them be just barely on the brink. Whether that meant losing one, or a great many. Or even winning! 'Ah, we won, but there are so many more battles to fight, how can we go on with so few left, fewer every year, etc. etc.'
It's almost as though the people founded by sex cultists with centuries long lifespans would have a high birth rate.
Well, part of it isn't so much that, as the fact that it's repeatedly said centuries long people who are fighting and dying. You'd think, attrition wise, that if they really did have such a high birth rate, they'd be running into, well, a few decades down the line of basically DE babies throwing themselves into battle.
Rather, in all the materials, from Malus' to Teclis+Tyrion to Gotrek+Felix, they're always described as centuries old experts and deadly experienced corsairs with centuries of murdering under their belts and sorceresses with centuries of learning their craft and making pacts, etc. Regardless of the casualties they take in other things, they have a, as Doc said, just a constant 'as many as they need' of these experts despite killing each other quite often, assassinating each other, as well as regular fights.
I don't think I ever saw a single reference or thing where a DE went 'But I'm only a half a century old! Like my thousands of brothers and sisters! I'm not nearly as fast/strong/experienced as you, eight century year old dread lord!" or anything even close to describing a...young DE, really. Despite the constant ravaging competition between said dread lords, and sorceresses, and corsair captains, etc.
Plus, I would expect that if the DE could truly pull off a super high birthrate, having Alarielle visiting your settlement and wandering about Ulthuan as she does should vastly increase fertility and birth rates and such because, well, Isha (Goddess of Fertility) and such, so the HE should have a directly God-borne fertility rate. But...they don't.
It's quite the conundrum, canon-wise. It's the same for the Empire, and the dwarfs. The dwarfs can hold the citadel of K8P with 500 dudes and Belegar, because that's all that could possibly be spared despite it's importance and being occupied by both greenskins and skaven. Meanwhile, 10,000 dwarfs die in a mountain collapse or avalanche or whatever near Karak Azul and that's nothing more than a little blurb on the side for Grudge-lore. Empire constantly,
constantly loses villages and towns and such. Like, almost every novel I've read involves one of those going up in flames, or burning down in flames, or being plagued to death, etc. etc. and yet the Empire can still marshal armies for every province and fight back against humongous WAAAAGH!!s and Chaos hordes and so on and so forth.
It's something that one has to sift through, decide for themselves for their own pocket version, then iron out and hammer down what is and isn't canon for numbers. Or, for instance, their quest version.
