The problem with wealth inequality is that it's the same distorting forces of a monopoly. A small cadre use their wealth an influence to shape politics to serve their interests. Markets chase after small lucrative pools of customers. (For example, luxury condos get built, but affordable housing does not.) Education gets warped as the wealthy concentrate in small neighborhoods and thus improving those schools, while the rest fall farther and farther behind. The macroeconomy becomes more unstable as it's driven by the fads whims of the few. This instability and political disenfranchisement then leads to political instabilities and eventually sudden political upheavals where entire political, social, and economic systems are overthrown for sake of reform, but at the same time just leads to more extreme instability.

Until ironically, the wealthy simply leave (because who wants to stay in an a dangerous unstable place, when you can afford to leave), and let place that they set on fire burn to the ground, click their tongues and say, "Who knew this would happen?"

To think of it another way, no one puts all bets on a single investment. You diversify. That's what spreading the wealth does. It diversifies opportunity.