[prodmerc]

IQ is only a good predictor when you compare low average and borderline (who indeed are at a disadvantage no matter their conditions) with average and higher.

Average, above average and higher scoring persons' outcome in life will depend more heavily on upbringing and surroundings than anything else.

In fact, those scoring the highest may actually end up worse - addiction, depression, anxiety, loneliness, etc. - all because they live well below their potential because of their circumstances...