A person's achievements as an adult are greatly influenced by their family resources, personal talents, and opportunities, but one key factor is whether that person can persist in their goals, no matter the setbacks.
Any high achievement requires experiencing setbacks; conversely, any achievement that does not encounter setbacks is merely the individual's lower limit. For example, if you see someone excelling in their studies and smoothly progressing to a PhD and becoming a professor, it might just be because studying is easy and enjoyable for them, while they could potentially achieve much more.
How can one develop resilience against setbacks? My view is that the proportion of changeable factors in adulthood is very small; much of it may be energy injected during childhood. If a child is loved and encouraged to explore from a young age, they may have the courage to face the world. Conversely, if a child is often neglected or reprimanded, they may spend a lifetime seeking affirmation from others, and if setbacks are perceived as the world's denial of them, they may not be able to overcome them.
Of course, the above is just theoretical, but based on small sample observations, it's quite accurate. You can also draw your own conclusions based on your own small samples.