Wealth inequality is a growing concern in the world today, and this key idea explores the reasons behind it. According to Piketty, wealth inequality has been increasing over the last few decades, and it is likely to continue to do so in the future. Piketty argues that this trend is due to several factors.

First, the rate of return on capital investment is higher than the rate of economic growth. This means that those who own capital are able to accumulate wealth faster than those who rely on income from labor. This creates a situation where the rich get richer and the poor get poorer.

Second, inheritance perpetuates wealth inequality. Wealthy families are able to pass down their wealth to their children, who in turn are able to accumulate even more wealth. This creates a cycle of wealth concentration that is difficult to break.

Third, high salaries for top earners contribute to wealth inequality. The gap between the highest-paid executives and the average worker has been growing over the years. This means that a small group of people at the top are accumulating a disproportionate amount of wealth.

Piketty argues that progressive taxation is one way to reduce wealth inequality. By taxing the wealthy at a higher rate, governments can redistribute wealth and reduce the concentration of wealth among a small group of people. However, he also acknowledges that this is a politically challenging solution that may not be feasible in some countries.

Overall, the rising trend of wealth inequality is a complex issue with many contributing factors. Piketty's analysis of the problem provides valuable insights into the mechanisms that drive wealth inequality and the potential solutions that can help address it. The challenge now is for policymakers and society at large to take action to reduce wealth inequality and create a more just and equitable society.