Inequality isn't a problem.
Fairness is the problem when it comes to economic growth. People want to have a fair chance, not just one half taking all the benefits.
The fact that inequality exists is not the problem, it's the severity of the inequality that is the problem.
Take an extreme example - out of a population of 1000 people you have 1 person owning 99% of the wealth, with the other 1% distributed to the other 999. Does that seem like an efficient, properly operating economy to you?
Obviously there is some balancing needs to happen, the trick is figuring out where the fulcrum should sit for the most efficiency.
Inequality is great really. It incentivizes people to give extra effort for a reward. But gone too far, the efficiency of humanity will drop. There needs to be (and there probably is) shifts in wealth to keep things moving. Let's get those moon bases going.
Edit:
I was really hopeful for this Stanford resource, but I'm not even sure these "are facts that everyone should know".
> 10. Residential Segregation
tldr: Rich people and poor people don't live in the same areas.
> 13. Bad Jobs
tldr: Some people have bad jobs, and if you don't work full-time somewhere you're more likely to have a bad job.
This just seems like common sense. Was anyone surprised by this?
Certainly not horrified.