The most famous example of arch structure is Zhao Zhouqiao in China. We all know that Zhao Zhouqiao is famous for its long span and no piers. The reason why it is still strong and durable for thousands of years is because of the ingenious arch structure, which uses two shoulders to disperse the weight of the bridge and the weight of pedestrians and vehicles on the bridge. This principle is called the force dissipation principle in mechanics, which is to dissipate the force on two shoulders, so that it can be supported today even without piers.
The same principle applies to eggs. The vertical egg is arched, and the force is decomposed to all points of the egg, which reduces the pressure to some extent and the egg can bear more weight.