Late in life, a star of a set size can settle down to life as a neutron star, but is that the whole story? A free neutron has a half life of 10.3 minutes. What if neutrons are continually breaking up and reforming in such a high gravity state so that the star is actually a mixture of neutrons, protons, quarks and electrons?
This is what probably what happens inside the neutron star, and it forms a equilibrium between neutrons and protons, quarks & electrons.