> The cost of raising a child is enormous.

Honestly, the primary problem is still the mindset behind most times this line is written.

The cost of raising a child is enormous only if you consider the return a nuisance at best, which many seem to do. If you consider it very rewarding thing you want for your life, working for that a little doesn't seem all that preposterous anymore.

The same peope typically have no problem spending money on frivolous hobbies, toys, travel etc. they technically get no economic return for either.

There may be people who are economically barred from affording children, but most people set the bar at "I want kids with no strings attached".

The real reasons are that we've created a society in which many people no longer consider a rewarding experience they actually want, and those who don't want it no longer have it externally thrust upon them by cultural expectations or pressures as much. I think the latter is good, but the former may be a pervasive failure of character.