This example shows the distribution of billionaires across categories using a single pie chart. The chart is rendered as an SVG with colored slices, labels for larger segments, and a legend that displays each category's name and count. The code aggregates the CSV data with `d3.rollup`, generates the pie geometry with `d3.pie` and `d3.arc`, and assigns colors via `d3.scaleOrdinal` with a categorical scheme.