Neutrons are not Fundamental Particles

Standard textbook physics tells us that the neutron is a fundamental particle. However, it's well known that this particle cannot exist for more than about 15 minutes outside an atomic nucleus. Furthermore, when it falls apart it produces a proton, an electron and a neutrino in the process. This alone should put to rest the idea that neutrons are fundamental. Yet the idea persists.

Free neutron decay

The neutron is considered fundamental for obscure reasons that are difficult to grasp. I must admit I haven't been able to follow the reasoning myself. However, I don't see that as a failure on my part. Rather, I find it suspect that something so trivial as free neutron decay should be difficult to explain. Shouldn't it be easy to explain what's going on and why the neutron is fundamental, despite its fragility?

Seen in light of the theory presented in my book, the neutron is most definitely not a fundamental particle, and this can be explained in simple terms:

Neutrons are bits of inertial matter, and as such they must be hollow, as explained in my book. To stay inflated, particles of inertial matter have to have a repelling electrical force inside of them. This in turn requires the walls on the inside of particles to be electrically charged. If the neutron is fundamental, and not merely an assembly of a proton and an electron, it would have walls of neutral charge inside of it. This would not produce any electric repulsion. The neutron would collapse even before it was properly produced.

Not only do we have free neutron decay as experimental proof that neutrons are composite particles, we now also have theoretical reasons for this to be so. Neutrons are not fundamental particles, they are assemblies of one proton and one electron.