In general there is *some* correlation between success in dental school and success in private practice. My personal take on that is that it has much more to do with the drive and motivation to succeed in dental school carrying over to the drive and motivation to succeed in practice.
However, the reality is more often than not what makes one dentist more "successful" than another dentist very often has more to do with how that dentist treats their patients, and often staff too in front of patients, as a person rather that one's clinical ability.
Time and time again, you can see a dentist, who as a colleague you can see and know that they have GREAT clinical skills

, but might not be the most financially successful dentist where as a dentist who isn't as clinically proficient but has GREAT patient skills is doing better financially

. The reality is that most patients don't know the difference between a sub 20 micro crown margin and say a 50 micron crown margin, or the difference between perfect tertiary anatomy and a random tooth colored "blob" for anatomy. What patients do know is #1 how painful it was or wasn't while in the chair and #2 how they were treated as a person while in the chair. I no longer add "how expensive it was" since over the years I've come to realize that about 99% of all patients will always think on some level that you charge too much for your work, regardless of if you're the most or least expensive clinician in that area
In no means am I saying that one should sacrifice their clinical skills for the sake of their people skills, but one shouldn't also neglect their people skills and how they interact with their patients in this ever changing world. What might of been great a few years ago, may very well be tired and semi irrelevant now, and patients can pick up on that. The "best" dentists are always evolving and re-inventing themselves and their practices as time passes