Eh... the way I see it, having billionaires (or millionaires) hurts the economy much less than the cost of not having them- if we need billionaires to produce a good economy with stable, attainable jobs, then so be it.
I mean, sure, ideally we could split up their wealth and distribute it, but I think we can agree that this would fundamentally hurt the economy. The way to overcome this would be if the government literally came in and ran the job market. I'm not sure most people would actually want that.
I don't think there is any evidence actually supporting that claim.