One (admittedly cynical and disrespectful) hypothesis could be that some of the low-income people are low-income precisely because they disliked abstract reasoning in the first place, thus making them less likely to pursue their education.
To be honest, there are dozens of different ways to interpret this data.
There really isn't. You're letting your bias influence your opinion. Read the paper, draw your conclusions carefully, I wager you will have to change them.
Replace 'disliked' with 'incapable of,' and that hypothesis is neither cynical nor disrespectful. People with subpar cognitive abilities are less likely to move themselves out of poverty.
To be honest, there are dozens of different ways to interpret this data.