What strikes me the most when looking at many of the comments here is the blatant disregard for human suffering that extreme inequality and the resulting poverty cause. The current economical status quo is accepted as a given and all the harm it causes is dismissed with the shrug of a shoulder. "It can't be helped, the poor sods should have made better life choices to avoid ending up as janitor" is the attitude by wh…
Human life has positive ROI, as evidenced by the fact that our species has done better in the world over time. The largest returns are highly unpredictable too - the majority of "origin" stories for the greatest contributors to moving our species forward have come from modest beginnings.
So disadvantaging large swaths of the population with poor access to quality education or healthcare biases the system against the masses, and as a result, reduces the productive potential of that population segment. A janitor today may not be the next Steve Jobs. But his kid might, if given access to a good education and not burdened by needing to accept a "safe" work choice to support his parents.
In addition, that janitor is likely putting a much larger portion of his wealth back into the economy directly by purchasing "things." And in a global economy that revolves around mass production, it would make sense that economic policies favoring the spending power of the masses would be a key factor in the pace of innovation and moving industry at large forward.
If only Wall Street can afford 4k TVs, they'll be watching a lot of upscaled 1080p content. It's not until the janitors, electricians, etc (i.e. the masses) can afford the sets that they'll see the majority of content switch over to 4k. (This is a knowingly superficial but illustrative example of a larger principle).
Even in my own case - I have a pre-existing medical condition. If it weren't for Obamacare, I wouldn't have been able to co-found my startup, which last year (first operational year) did $350k in sales, and this year looks like it may hit $700k. I'd have needed a job that provided good group health insurance, and our company simply wouldn't exist.
We like to talk in the entrepreneur community about the need to take risks to be successful. But too often the community turns a blind eye to the fact that if you cut away enough of the public safety nets, the only people that will be taking risks are the people that either (a) have a personal safety net already, or (b) have such poor judgement in risk assessment that they are destined to fail.
Social programs and policies aren't "entitlements" or things we should be doing from simply a moral standpoint - they are economic "growth" programs and make a great deal of sense if you look at the broader picture and with a perspective of 10, 50, 100 years instead of fiscal quarters.
Income inequality unchecked is going to destroy our national competitiveness the same way an executive cutting themselves a massive salary and underfunding corporate reinvestment is going to drive that company into the ground. We're cutting national reinvestment in order to further advantage the previously successful (several generations past in many cases), at the cost of the potentially future successful.