For some reason, there are smart people who think that meritocracy works: work hard and things will be good for you. The problem is that in many cases working hard (as in building up a startup) does indeed give people the opportunity to rise in society. But it is not true in all cases at all. And so the negative statement "if you are struggling you didn't try enough" is completely flawed.
First, in capitalism, a work's remuneration is supposed to be related in a way to the perceived utility of that work for society in general. Second competition means that a work's remuneration is inversely proportional to how easy it is to perform.
Using those 2 propositions, it becomes obvious that jobs with little utility and high competition have a remuneration that tends to go down to 0 (fast food, taxis, etc.). So in these cases, no matter how hard you work, your pay can only go that high.