CEOs work harder every hour than their wage slaves do every season.

[kılıç_mehmet]

What I want to know is, what is the justification for CEOs making obscene amounts of money off the backs of people he pays so little that those people can't afford to live a life secure from poverty?

In my world, there is no such justification. But in an internationalist, globalistic capitalist worldview, self-interest is the only justification they'll ever need.
That's what today's worldview gives the people.
They do not have to think about their workers beyond of how they view a piece of machinery.

I can never be a libertarian because I cannot come up with even the slightest justification for the proposition that people who literally have no material need should be able to continue accumulating unnecessary personal wealth at the direct expense of people who can't afford basic survival with (or in some tragic cases, without) government assistance, let alone a moderate, minimally secure lifestyle.

I don't think that anyone that works for a corporation or in a factory as skilled labor is unable to afford a minimally secure lifestyle.
That's not even the case in my country.