Why does a nucleus form?
I'm learning about decay of heavy elements, and it occurs because the like-charge of protons will overwhelm the strong force at a large enough nuclear radii.

i can accept electromagnetism, and that things have inherent charge, and like charges repel.

is the strong force just an inherent thing? hadrons just are attracted to each other, inherently?
i guess, given a large enough sphere of protons/neutrons, obviously there's a weaker interaction between two of the most opposite protons on the perimeter of that nucleus. and given a large enough radius, the "inherent attraction" of hadrons is not stronger than the repulsion of like charges.

but, why do atoms form how they do? like, why protons and neutrons?
why is it more stable with neurons in the nucleus, than with just protons? you'd have a smaller radius and therefore a higher attractive force. why is helium-2 very unstable, but helium-4 is not?

and what of neutron stars? you can have a cohesive mass of pure neutrons. could you have a stable sphere of say, 10 neutrons or something?