There is scant evidence backing up that "usually". You obviously need some incentives for people to take risks or work hard, but no Zuckerberg or Gates or Kamprad or Ek would have been discouraged if his marginal tax rate had been 10% higher.

Indeed a social safety net such as the one you could fund with such a tax increase may make it easier for people to start businesses, because they know failure wouldn't mean starvation.

It's also pretty clear, that success requires more than motivation. You also need education, and access to (infrastructure/decision makers/capital/potable water ). Inequality, in the sense that the American right glorifies, stands opposite such access. The Ayn Rand crowd seems to really enjoy their phantasies of inflicting harm not only on the poor, but also descendants three generations down the road.

And so you get some people to argue about "wealth creation" in a country that has created the greatest wealth ever amassed by humankind but also has major cities whose drinking water is unfit for human consumption.