I find it hard to take seriously for this reason: the proton is not an elementary particle but rather a composite particle whose mass is the sum of the masses of quarks in it and also the binding energy of the gluons and the electrostatic binding energy. The mainstream way to calculate it is a very complex computational Lattice QCD problem:

https://indico.phy.anl.gov/event/2/contributions/19/attachme...

The ratio of the electron mass to, I dunno, the top quark mass might be a fundamental quality that can be calculated in a few lines, but I've been seeing outsiders write simple formulas for mₚ/mₑ for most of my life and haven't been impressed.