The tip is sharp so as to provide a greater pressure over a smaller area in order to penetrate easily with a less force.
If you invert the pin and try to penetrate the blunt side in the wall a force 10 N
it will not penetrate as the pressure is equally divided over a large area So it will not penetrate into the wall but if you inverted it agiain try to pierce it into the wall of the sharp tip with the 10 N force then it will easily penetrate into the wall .
Pressure is inversely proportional to the area and ,
Pressure is directly proportional to the Force applied.
hence , the formula
Pressure = Force / Area
I hope u are satisfied .