Stars release huge amounts of radiation from their surfaces while on the main sequence. why is this necessary if a star is to maintain hydrostatic equilibrium?

Hydrostatic equilibrium is the energy balance between two forces at the stars: the inward force of gravity (due to the mass of the star) and the outward gas pressure (due to the energy release from nuclear reactions in the core of the star). Hydrostatic equilibrium is important because it holds the star together.