Nonmetals rarely lose electrons in chemical reactions because?

The reason for this is because nonmetals, have close to fulfilling an octet and need to gain few more electrons to do this, not to lose more. Nonmetals, because of the fact they need only few more electrons to satisfy their octet they would receive or share electrons to do this.

The property that nonmetals have are that they are very electronegative, they possess a strong affinity to pull electron density closer, because they possess fewer electron shells and possess even protons this allows for this.

They are all full and don't need any more electrons in there outer shell.