This seems completely wrong to me. If you look at who is the top 0.1% it's either inherited wealth, a few professionals (lawyers, certain medical specialties, etc.) who own their own practices, or people who've managed large groups of people (i.e. business executives). The third group is overwhelmingly full of people with good social skills, and skilled professionals are almost always personable too.
We keep hearing that. (Because it sounds good).
It should be true because it's not all that hard to keep wealth increasing at least modestly - and let time do the work. But take heart! "The Missing Billionaires" argues that in practice inherited wealth is reliably lost over shockingly few generations.