The claim that Pi equals 4 is based on a flawed interpretation of a diagram that misrepresents the relationship between the circumference and diameter of a circle. The discussion highlights that Pi is a mathematical constant approximately equal to 3.14, derived from the ratio of a circle's circumference to its diameter. Participants emphasize the importance of understanding geometric principles and the correct application of mathematical formulas. The thread encourages users to analyze the diagram critically and recognize the errors in reasoning. Misconceptions about Pi can lead to significant misunderstandings in geometry and mathematics.