Why did large sailing ships usually stop at three masts?

Why did large rigged ships usually have three masts rather than more?

Three was usually the practical balance between sail power and the added personnel and handling complexity of more masts.

Three masts were a common design solution rather than a hard technical limit. Larger numbers were possible, with examples reaching seven. Every additional mast increased the rigging to handle, the crew required, and the complexity of organizing and manoeuvring the ship. For many large sailing vessels, three therefore offered a practical balance between sail power and operating cost.