Housing and food are pretty much completely owned by a small handful of wealthy individuals.

This is almost certainly not true. I own my house, grow a small but significant percentage of my own food, and could easily invest a little more time and money to be self sufficient in both those areas. And I'm fairly representative of an average american in many ways. The reason some people don't have sufficient food or shelter is because almost everyone is chasing something more than the basics - nicer cars/clothes/TV/vacations/etc.

I don't know what they could possibly be wanting for or seeking with all of the money that they don't spend helping others and improving society. What I can say, though, is that there is no end they could possibly seek, except for simple individual power and dominance over other people, that wouldn't be more quickly and effectively reached with more healthy, well-fed minds on the job.

This is definitely true, and really represents a commitment problem. The problem is so big compared to the individual wealth of any one person, that no real benefit can be seen from individual action. If the "ruling class" really wants to be better off by having control of more fit proletariat they need collective action to make it happen. Which sounds a lot like raising taxes on the wealthy to fund social programs.

I'd actually agree that there's a good, purely selfish, case to be made for that. The problem is that people are both very risk averse and very bad at predicting the future (especially in the case of complex systems, like macroeconomics and social systems). So, instead of taking what's likely the best course of action, many people (rich and poor alike) take the safest choice instead.