“The biggest mistake, in general, I've made is to put too much of a weighting on someone's talent and not enough on their personality. … It actually matters whether someone has a good heart, it really does. I've made the mistake of thinking sometimes it's just about the brain.”
Talent Versus Personality
This was the closing audience question at Musk’s SXSW 2013 keynote: what was the biggest mistake he had made? He paused a long while before answering. The wording here is reconstructed from same-day press and a contemporaneous transcription of the session video, not the recording itself, which is no longer cleanly accessible online; the surviving transcripts agree on substance and differ only in small words.
Musk does not present this as a lesson he has already learned; he says he is still trying to correct it. Almost anyone will agree that character matters and then make the brilliant hire they had doubts about anyway, which is what makes the admission useful: the hard part was never believing it.