Is fertility so important?

Maybe the other western countries are equally infertile, but just allowed many immigrants in (which counts are population expansion) that also have more children on average.

How are Japan and Korea holing out? They are further down the infertility down-spiral.

Lol, what on earth makes you single out Poland as the single western country not in decay right now?

That impacts the whole developed world, it’s not a polish issue

The very consumerism that has made it materially wealthy has fucked up its citizens' priorities. Indeed, because the wealth differential over the last 30 years is as steep as it is - and because people are generally petty - it actually creates a perverse incentive to prioritize wealth accumulation over family life just to "keep up". You don't want the Joneses to outdo you. You don't want to seem shabbier.

So, maybe rapid growth combined with consumerist impulses is a deadly combination for a society. If only rapid growth were combined with healthy and wise priorities...