Why does helium have a stable electron arrangement with only two electrons?

Helium’s stability arises because its only electron shell, the $n=1$ shell, is completely filled with two electrons.12

According to the Pauli exclusion principle, an orbital can hold a maximum of two electrons, provided they have opposite spin states. In a helium atom, the $1s$ orbital—which constitutes the entire $n=1$ shell—is occupied by these two electrons. Because this shell is full, helium is considered a closed-shell species, making it chemically inert and stable.13

While many other noble gases achieve stability through an eight-electron arrangement known as the octet rule, helium is a unique exception that achieves a stable, closed-shell configuration with only two electrons.134