I see no evidence that the billionaires are especially competent. They are never super geniuses, consistently capable of seeing what nobody else sees. At best, they have one or two bright ideas a short time before everyone else. They were the ones who happened to be in the right place at the right time. Often, they push out the ones who are more competent at everything except pushing other people out.
I concur that voters are extremely bad, but when the billionaires become oligarchs, they are exactly the dictators and technocrats you warn against. The voters are nominally in charge but they have enormous power to influence the voters. And one of the tools of that influence is their self mythology of being skilled more than lucky.