Why is there a press stud on the peak of a flat cap?

The press stud on the peak of a flat cap, often referred to as a "button," serves both functional and aesthetic purposes. Functionally, it helps to keep the fabric of the cap securely in place, preventing it from flapping or shifting during wear. Aesthetically, it adds a classic touch to the design, contributing to the cap's distinctive style. Additionally, it can provide a point of interest that enhances the overall look of the cap.