That is simply and obviously not true. The rich do not have the same responsibilities as everyone else. I believe that the more money one makes, the more they should contribute to society. And since people are naturally greedy and likely won't voluntarily give up some of their income to fund the military, education, services for the poor/disabled, etc, we have a tax system in place. A flat tax system would leave the lower class paying more than they should and the rich not paying enough. The uber-wealthy in the US pays fewer taxes than the middle-class on average. How is this fair?
Capitalism is not inherently corrupt. With the right amount of regulations and oversight, a capitalist economy can run smoothly with very little corruption. Like Finland for example, it has been called the "capitalist paradise". There is a market economy there, yet poverty is very low, everyone has healthcare access, wages are fair, while there still are many large corporations in Finland that are able to churn out immense profits. Free-market capitalism, however, relies on corruption; the exploitation of the poor so that the capitalists in control can be uber-rich. Capitalism does not free people from being treated unfairly; under free-market capitalism, workers, usually lower-wage ones, are oppressed by the capitalist class in the sense that they barely have enough money to get by (leaving them no buying power) long and inflexible hours, little or no sick/vacation days or paid leave, and if they protested any of this, they'd almost certainly get fired. This is not freedom by any means. That being said, there will always be poorer people in any society and people who own corporations have the right to wealthy, but this does not mean that low-wage workers should be injusticed just so the rich can be rich. Think about all the workers protections we have in first world countries (America included) like no child labor or unsanitary/hazardous conditions, ability to protest/strike, and equal pay laws for women and minorities. The free market didn't do this. Common people protested and progressive politicians listened to them. Don't you think there's a reason why during these times, big corporations would fight hard against these reforms? Because they care about their bottom line far more than the welfare of their employees. There are still many strides that need to be made.