The research, by Don Moore of Carnegie Mellon University in Pittsburgh, Pennsylvania, shows that we prefer advice from a confident source, even to the point that we are willing to forgive a poor track record. Moore argues that in competitive situations, this can drive those offering advice to increasingly exaggerate how sure they are.
Now, this preference would be irritating but tolerable if cockiness was at least reasonably well-correlated with competence in practice, so that it wouldn’t usually be a mistake to plump for the cocky judgment over the quiet one. And it would be a little better if the two were actually uncorrelated. But as a famous paper by Kruger and Sunning showed, people who are bad at what they do are generally also incapable of understanding that they suck — and this directly contributes to inflated self-perception. So, incompetence tends to make people cocky and people prefer cocky judgements over demonstrated expertise, which is pretty much the worst of both worlds.