The rest of your post sounded rational. This part doesn’t.
Failure to build more units (NIMBY) and properties being held as investments (non-US nationals are significant in some markets) are the two causes I would point to. Of course every additional family that needs housing drives up the cost a little, but I really don’t think that can be responsible for the massive increases in housing valuation.
The other big issue is density is expensive; it costs much more to build an apartment at the 10th floor than a detached house. Combine that with density being inherently a bit shit, you get less quality and less housing for the money spent.
There are several issues with your position. Of course there are other factors, but it is inherently disingenuous and dishonest to ignore the fact that just alone since the year 2000 at least 45 million foreigners and their children are in the USA that would not have been here just based on natural population growth. So it's up to you if you can rationalize hard enough to ty to make an argument that adding 45 million additional people to the population would not have had some measurable impact on the "massive increase in housing valuations".
Genuinely, were you at all aware of just how many foreign people had come to the USA and then had children?