I don't subscribe to this theory. I personally think most don't get rich because they don't acquire an education that will allow them to capitalize off of their talent and natural ability. In the hood we were never taught to pursue an education past high school. To this day I'm the only male from my neighborhood to get a college degree. I'm the only male in my family to get one as well.
Another reason most people remain in the conditions that they were born in is because they're taught to conform to a typical 9-5. Once again using me as an example, in high school all the older heads thought that getting a warehouse job was coming up. My first year out of high school I got multiple warehouse jobs and quit them all. I told myself that college could never be harder than that shyt and I went from being a 2.0 student in high school to being a 4.0 student in college.
I say all of that to say that people usually become stagnant/content because they become products of their environment and they don't pursue their dreams because they're taught to go the safe route which is a typical 9-5. Its so many dreamkillers out there that most just fall victim to the traps of drugs or alcohol which often kills ambition.
The game isn't designed for everyone to be up but more could be up if they actually knew how to monetize their passion and were bold enough to try it.
As far as the top part goes, people who have the actual drive to be rich are going to do so regardless of their level of education. School for the most part encourages most to be mindless drones as a sort of social conditioning, you simply either have the ambition or you don't. There are people with a shyt ton of nice degrees but have still only made it so far because they don't have enough drive and aren't willing to put in the time/sacrifice needed, nor take the risks. The bottom bolded part is the typical result of this country's education system. Besides, these people with exceptional drive and high ambitions already had them from a young age for real, I do agree that environment definitely does play a factor though. I don't see most who would want to become rich doing so if they already havent got a plan and shyt going by a certain time. Like someone who is already working a typical 9 to 5 while in their 20's and shyt isn't going to up and be well on the road to riches because by then, they've already subscribed to the every man's life too long. Another thing that definitely factors in that most will pretend doesn't matter, is luck. Luck is definitely involved because the road to riches is paved with broken down vehicles of people who thought they had it but missed their windows. It takes a special kind of person to make it from the bottom, and very few are able. This is also why capitalism is the way it is, as far as being wealthy, few win, most lose.