Are personal qualities the sole reason one becomes an outlier?

No, personal traits are not the sole factors determining one's success. In fact, in Outliers, Malcolm Gladwell notes that personal traits are often not even the most important factor. Each section of the book covers different ways that success is impacted by outside factors. For example, among Canadian hockey players, one's birthdate is important. Those born earlier in the year are often much stronger and more developed than those born later in the year. They perform better in practice and are selected for additional training opportunities, further increasing the gap between them and younger players in the same class. Cultural factors also determine the skills people develop, leading to significant differences in skill levels in specific subject areas between cultures.

No. Innate talent is only one of the attributes needed to become an outstandingly successful person. Malcolm Gladwell begins with these definitions of “outlier:”
something that is situated away from or classed differently from a main or related body.
a statistical observation that is markedly different in value from the others of the sample.
We’re used to hearing the stereotypical stories of folks who overcome insurmountable odds to make their rags-to-riches climbs to the top of their fields. After Gladwell analyzes the histories of Silicon Valley computer geeks, Jewish immigrant garment workers, Asian rice farmers and math students, Korean pilots, and many more examples, he comes to another conclusion: the stereotype is a myth. There are almost always hidden advantages of some kind. Cultural legacies and perfect timing by the calendar can combine to produce the right people doing the right thing at the right time. Sometimes, it’s a matter of where you were born and when, and how much time you could devote to your project.

They are products of history and community, of opportunity and legacy. Their success is not exceptional or mysterious. It is grounded in a web of advantages and inheritances, some deserved, some not, some earned, some just plain lucky—but all critical to making them who they are. The outlier, in the end, is not an outlier at all (285).