I think you're spot on. And all of the various theories and analysis are pretty laughable if one has any sort of historical context.

- "People don't have kids because they're afraid of climate change" - Wildly overestimates the number of people who figure climate change into their life plans, and it discounts the numerous catastrophes people have feared and experience in the past while continuing to have high birth rates. - "People don't have kids because everything is too expensive" - My father-in-law has 11 siblings and they grew up in a 2 bedroom, 1 bathroom home. His story is not unique.

"having kids is almost completely intentional"....in countries where this is the case due to birth control, abortion, feminism (and other cultural shifts), the birth rate plummets.

Delving into the reasons why people opt to have fewer or no children when given the choice consistently across races, religions, cultural background, etc would be a book-length endeavor, but to me it really is that simple. There are numerous reasons someone wouldn't want to have more children, and they tend to find one of them when given the choice.