This doesn't surprise me at all. Based on my observations, I would say that at least the bottom 80% lives solely on income from labor, and accumulates no wealth

This doesn't surprise me at all. Based on my observations, I would say that at least the bottom 80% lives solely on income from labor, and accumulates no wealth. Of the upper 20%, some live below their means, some earn slightly more from their labor than necessary to live, and others make enough to accumulate capital. Once you begin to accumulate capital, you earn money from the capital itself. Some accumulate enough capital to earn enough income to quit earning income from labor entirely. Some use the excess capital income to accumulate even more capital. Capital is then passed down to heirs. So the accumulated capital is about equal to new capital generated.