They never really say in the article.
I have been to Denmark many times and it strikes me as considerably more homogenous than the UK or the US.
Funnily enough, Denmark is a few places below France in "ethnic fractionalization", yet somehow, racists worldwide insist that France has become a shithole because of immigration.
Truth is, these people are simply afraid for their cozy jobs, that's all there is to it. Derivative states of mind like Stockholm Syndrome and Sunk Cost Fallacy are quite normal to appear in these conditions.
On OP: I could not agree more. People always downplay their fuck-ups, that's sadly part of being a Homo Sapiens, but the lack of awareness is still both despairing and hilarious to watch.
And finally, C/C++'s niches have decreased but these people will not adapt, of course. Almost anything I've done with those languages 15-20 years can today be done with Rust. Or if you are on a tight time budget -- Golang, and you still won't lose too much speed.
But sure, "nothing can be done, these things sometimes happen". Sigh.