Earlier quoted context omitted.
If that were true, then why do poor people have a disproportional high chance of having their children grow up poor?
Because the vast majority do not have that drive, and simply fall into the same pattern as their parents.
In response to your point, I think that the problem is much more one of opportunity than drive. For example, I went to a private high school that costs slightly more that the poverty line for a family of 4 (as did my 2 siblings). My mom was able to leave her job, and stay home with me, where she taught me the fun parts of math (knowledge which made school math classes bearable). Later, when I was in high school, my mom started volunteering, where she met the wife of a fairly well known computer science professor at a local university. She arranged with him for me to get a summer internship there, after which point I had a brief phone interview, where I answered almost nothing about my abilities. A few days later, I got an e-mail saying that the robotics lab (where I would have prefered working) couldn't take me, so I had to settle to work in his lab, at 10$/hour - after I offered several times to work for free. While at his lab, I did a reasonable amount of work, but nothing that impressive. One of the things I did was help one of the graduate students with their research project, which involved a web crawler to collect data, and a machine learning algorithm to analyze it. I did some incremental improvents to the crawler, but nothing that impressive. I also wrote the machine learning "algorithm" which was a 250 line program that took data from an sql database, and fed it into a machine learning library, then printed out the results. For all of my being driven, I ended up being a co-author on a published research paper before I even applied to colleges.
Of course, I am just one person, so we cannot generalize from my example to say that it is the parents that do the work. What we can say is that the children of poor parents are disproportional likely to end up poor. This means that you can, with a high degree of accuracy, predict a childs future success before they are born. If this is the case, they we cannot blame the child for his failures, because we knew that he incredibly likely to fail before he even had a chance to influence his own life. This leads us to the conclusion that there is something going on outside of the control of the poor that is making it difficult for them to improve their lot in life. Looking at it this way, we might notice that the rich tend to spend large sums of money sending children to schools that the poor cannot afford. The rich tend to be more available to their young children, either by leaving their job, or only having 1 job. The rich know other succesfull people, who are an automatic network to get their children jobs and such.
In fact, looking back on my own life, and the lives of many of my rich classmates, It seems like we also tend to fall into the same patterns as our parents; those patterns just happen to be successful. This is almost the definition of a rigid class system, and it is something we should be working on moving away from. In an ideal world, even if you knew everything about the parents of two different children, you should have no way of guessing (with better accuracy than a coin toss) which of the children will be more successful.