Private investment is crucial for economic growth, especially in poor countries like those in Sub-Saharan Africa. This study looked at how different countries in the region accumulate capital. By combining different economic theories, the researchers found that countries with higher incomes tend to accumulate capital faster, leading to a gap between public and private investment. Factors like profitability, investment costs, and public infrastructure play a big role in how much capital is accumulated. The study's findings were supported by real-world data, showing that the predictions closely matched actual outcomes.