What's the root cause of inequality? There are certainly historical causes of inequality (e.g. slavery, feudalism, colonialism). These root causes are largely in the past, though they have modern residues (e.g. racism, sexism, western chauvinism) which contribute to inequaliy. I think they are often less important than how already existing inequality is amplified by cumulative advantage dynamics (the rich get richer). A wealth tax directly reduces the amplification and wealth can be redistributed to reduce inequality (not just of wealth, but of education, skills, and status too) on the other end.