I found this interesting note in one of my textbooks,
The enormous strength of the electromagnetic force compared to gravity is evident in our daily life. When we hold a book in our hand, we are balancing the gravitational force on the book due to the huge mass of the earth by the 'normal force' provided by our hand. The latter is nothing but the net electromagnetic force between the charged constituents of our hand and the book, at the surface in contact. If electromagnetic force were not intrinsically so much stronger than gravity, the hand of the strongest man would crumble under the weight of a feather! Indeed, to be consistent, in that circumstance, we ourselves would crumble under our own weight!
What does this mean?
Best Answer
The notion of "weak gravity" is "not even wrong"! It's comparing oranges to apples: it's meaningless to compare a dimension-full interaction (gravity) with a dimensionless interaction (standard model interactions such as the electromagnetic force), if no circumstance (e.g the specific charges and masses in comparison) is provided.
The Nobel laureate Frank Wilczek actually wrote a whole book ( The Lightness of Being) about what should be the right question: Given that the "charge" of the gravitational force is mass (energy tensor), the correct question is why are the masses of the elementary particles so small compared with the Planck scale?
This leads you to the nagging issue of natureness/hierarchy problem (the unnatural gap between the Planck mass and the weak scale/Higgs mass). As of yet, mortal physicists are still scratching their heads and fretting about this nasty "naturalness/hierarchy/fine-tuning problem". The world’s best minds are loosing sleeping on it (ask Lisa or Nima) and yet there is no answer.
To give you some thought experiment of "strong" gravity:
If the electron mass is increased to the mass of a flea egg ($10^{-8}$ kg, the plank mass), the gravitational attraction between electrons will be in balance with the repulsive electronic force. In technical jargon, the Schwarzschild radius and the Compton wavelength are of the same order for this case.
If the electron mass is increased to the mass of a chicken egg, the
gravitational force between electrons will trump the electronic force and electrons will be crushed into an electron black hole by gravity. Of course, true quantum gravity effects will be the dominant one in this case, the conventional semi-quantum black hole reasoning (a la Stephen Hawking) shall be taken with a grain of salt.