"Under capitalism, man exploits man. Under communism, it's just the opposite."
John Kenneth Galbraith
The idea that hard work is worth money is completely bogus. Hard work is only worth something if it produces something that others value. It's the production of things of value that counts, not the work.
This is easy to demonstrate: I can bust my butt all day long breaking a big rock down into a pile of gravel. At the end of the day, I may have worked harder than all but a tiny percentage of the rest of the population. However, unless there is some fabulous market for my gravel, all of my work isn't going to earn me anything.
What counts is whether you create anything that your neighbors value, not how hard you work. The "thing of value" doesn't have to be material, either. It can be an idea, or even the location of a thing. Merely moving something from one location to another can increase it's value.
The great thing about capitalism is that it lets the collective public sets the value of things. In communism and socialism, the state has a say (the only say, with communism) in the value placed on things. This invariably leads to values that are inconsistent with reality. This is why capitalistic societies have to be rough on monopolies - they screw up the system by being able to set unrealistic values on things.
Still Later addition:
About Family: it's true that families in capitalistic societies can build up lots of capital and thus become rich. This isn't nearly as easy as it used to be (at least in the US and Great Britian), however, since estate taxes and other forms of confiscation level the field pretty quickly. Even worse, the fortune must be divided among many heirs, now that first-born sons have no legal advantage in court.