While it is true that the electromagnetic force of a single electron is about 10^42 times stronger than its gravitational force, this just means that the force it exerts is equal to the gravitational force associated with its mass. Since the mass of a proton is 1.6 x 10^-24 grams, and the mass of the Earth is about 10^27 grams, a single cosmic ray will have no affect at all on the Earth. Even their accumulated mass over billions of years probably does not exceed a few hundred grams.