The problem with some notions of equality is that they don't take into account the fact that money, like everything else has diminishing returns.
About ten years ago researchers looking at this question discovered that while perceptions of personal success do continue to rise with income, income above $70,000 ($98,000 in current dollars) has essentially zero impact on emotional well-being -- the actual quality of life experienced by the individual on a day to day basis. In other words while our wants are flexible, our actual needs are quite modest.
This suggests to me that if you look at $98,000 as a consumption level, and factor in technologically mediated productivity changes, practical equality is something achievable in the historically speaking near future. A few countries are close to achieving this; if you look at the countries with the highest reports of well-being they're all wealthy countries with a low gini coefficients, which means that they have the largest proportion of people with solidly middle-class incomes.
In general I don't see any reason to care if someone wants to become the next Elon Musk, except so far as such people are able to buy politicians with their money. When politicians are working for the super-wealthy they're putting their efforts into things that will make literally nobody happier.