Isn't this an obviously biased sample? People who work at GCHQ can't talk about it, even if they enjoy it.
And for the few who are allowed to discuss it and enjoy working there they won't talk about it because, as you say, look at the HN discussion.
You just need enough, given unlimited computational budgets.
From a US perspective, Britain has low salaries in the private sector, but the civil service is even worse.
You would have to squint carefully at the benefits before joining.
You have to have quite the vantage point to have insight like that.
It’s more than likely that you all on the other side of the Atlantic aren’t our betters
Best of all, I get to work on systems which touch entire populations.
I guess Type-X personalities need not apply.
All of which has essentially led to the proliferation of greymarkets for exploits like Zerodium et al.
The situation is likely far worse for the States than the UK as the salary differential is greater and the agencies can only hire citizens. Do note that the US government is now the biggest buyer of malware on the planet, not really that surprising when you look at the circumstances.
One of my friends is an academic computer scientist, working on steganography, specifically steganalysis -- trying to do the inverse problems like "given 1e12 cat pictures, find the one with hidden information". GCHQ often like to talk to him about his work.
He has spoken of it being filled with mathematicians too socially inept to have an academic career...