It's not like we needed a study, though, because this point is self-evident on this site. Raising high-IQ children is EXPENSIVE, and failure to provide certain interventions can set these children up for failure. For a family that can't afford the investments in time and resources...
I think that this confuses "raising a high-IQ child" with "grooming for material success."
It's
not necessarily "expensive" to enrich a PG child. Even living in a non-urban, fairly blue-collar environment, there are libraries, the internet, and homeschooling opportunities, open source resources, etc.
But it
is expensive to TigerParent. What
costs so much, ironically, are those things that appeal not solely to PG children and their parents, but the things which are also trappings of high SES: private music lessons, travel, competitions, golf/polo/fencing/rowing/horses, designer camps/classes, etc.
I'm not dismissing the value of those things. Well, maybe I
am arguing the
value of those things-- from a purely monetary standpoint, I mean. I'm not sure that they do deliver "value" but I see why they are appealing.
I'm just stating that they aren't as strictly
necessary as many of us have been conditioned to think.
For example: one
can spend thousands each year on just math enrichment/education for a PG 3rd grader. OR... one could spend about $25 USD for Singapore Math's Primary Mathematics (2 full years, even!) and a few hours a week of a parent's time, which is less (by far) than even most standard packages from American textbook producers, and is certainly better quality pedagogically speaking.
Is the larger expense "necessary?" I don't know the answer, but I do know that we chose the $25 route. Maybe we're just 'cheap' that way.