Since youre beating around the bush, allow me to start.
I personally think affordability plays a role, but I think the driving factor, that applies to all developed countries and why we don't see people's pet ideas being common threads (socialized medicine will solve it! except in every developed nation with socialized medicine) comes down to hedonism, decadence and consumerism. People are living for comfort, entertainment, short term enjoyment, they're chasing shiny new things and they don't want to give that up to do something selfless like create good people. They don't want sticky hands ruining their new leather couch.
Prices going up aren't the cause, they're interlocked intimately as a symptom in a feedback loop. People aren't having kids so they can eat Korean barbecue for lunch every Tuesday, and so they have all this money that they're not spending. Or were, because everybody figures they can squeeze a few extra bucks out of them, and that adds up. Prices are going up because people are childless and so are more flippant with their money. Prices and fertility rate are interlocked tightly and one does not simply cause the other.
The only way out of course is that people accept a lower comfort level and buy only long lasting things that they actually need. But that's not going to happen, and that has a systemic cause too. I'd love it if you replied with your thoughts on what I've said, your 6+ factors, no matter how hard to swallow. I know for a fact most people reading this aren't going to like my premise that they are not having kids because they'd rather encase themselves in a constantly 73°F expensive memory foam ball, complete with genital stimulation and endless scrolling goggles. Scare some people off with me?