Again, one instance of upward social mobility doesn't make the American dream real. The US has some of the lowest levels of upward social mobility. Corporations hold monopolies, making it impossible for small businesses to make it big without some magical innovation. In the 1940's, 90% of people could make it up the ladder. Maybe not to a CEO, but a promotion nonetheless. In the 1980's, that number was 50%. Currently, Denmark, Norway, Finland, Canada, Sweden, Germany and France all have higher rates of upward social mobility. And if you really think pay is entirely dependent on how hard you work, that is simply untrue. Currently, in the US, only 28% of doctors are paid based on the quality of their care. Waiters who give excellent service only get an extra 1% in tips. There is the occasional success story, but many people don't even get an opportunity to get a promotion. In a survey of 41 countries, the US ranked 27th.
https://www.economist.com/graphic-detail/2018/02/14/americans-overestimate-social-mobility-in-their-country
https://worldpopulationreview.com/country-rankings/social-mobility-by-country