It is more energetically stable to do that. Nature prefers to have a low energy state. If you go somewhere in nature you will usually find a low energy state object or material.
When atoms come together to form ionic or covalent bonds, they form stable associations that change the properties of either atom alone. These new molecules exhibit unique emergent properties. A molecule exists when two or more atoms join together by forming chemical bonds.
Cells are able to re produce themselves without other cells needed. If cells need others to make more then how would that work and plus we wouldn't have the theory of cells existing.
