Can you explain why you say that? It seems you're suggesting that there is in fact a correlation between genius, or at least effective management, and unkindness. Is that what you meant? If so, why?

I can see how high high achievers could tend to be extremely focused and driven, which in some cases would present in this way. I wouldn't expect it to be the norm though; do you believe otherwise? How do you know?

I guess the parent is saying that there are lots of people with nasty behavior who are successful - may be not bill gates level successful, but successful nevertheless. Just a guess though