Even if wealth and income will roughly fall along a Pareto distribution (plausible, but needs some argument), that doesn't mean the 80/20 is universal. Only some Pareto distributions (characterized by certain parameters) display the 80/20 principle.
e.g. the Gini coefficient for an idealized Pareto distribution displaying the 80/20 principle is by definition 0.60. But Gini coefficients can obviously vary a lot from that, so societies definitely can exhibit either more or less wealth inequality.
e.g. the Gini coefficient for an idealized Pareto distribution displaying the 80/20 principle is by definition 0.60. But Gini coefficients can obviously vary a lot from that, so societies definitely can exhibit either more or less wealth inequality.