Is that true? All of the protons repel all other protons with the electric force and attract with the gravitational force, and it seems like gravity is just much weaker at all distances...
I haven't thought about this very hard though.
Now think of 10^50 protons in a line. They're all experiencing net gravity towards the middle.
With gravity, A is attracted inward, B is not attracted, C is attracted inward.
Of course, in practice, we don't know what the inside of a black hole is like, as quantum gravity is very much unsolved.
So the conclusion is any proton star would just explode? That's what I already thought.
Even if you make the argument that the energy complicit in the strong/weak forces is cumutavily much greater than the energy due to gravity, I'm still not sure "weak" is the right word for the job...
Gravity onstensibly runs at infinite speed over infinite area (the effect of gravity waves non-withstanding).
(Edit because we got a little confused in the replies: If it were all protons, they would repel and overcome gravity. But real matter isn't that, it's always protons and neutrons and electrons with close to no net repulsion so gravity wins.)
Similarly, radioactive nuclei (alpha emitters and spontaneous fission) happen because the electromagnetic repulsion exceeds the strong force, which has a very short range and doesn't reach across those large nuclei.