Think one electron.
Assume that it has finite, nonzero size.
It has electrtic charge as well as mass.
Think that the electron is spinning around z-axis.
Then, we can think the electric charge distribution function and mass distribution function of one electron.
In the spininng electron, there are Coulombic repulsion force, centrifugal force and magnetic force.
The former two forces act to explode the electron, but the last magnetic force acts to compress the electron as if it keeps the electron in one piece. There must be a balance between these forces for an electron to be.
Attached a trial calculation file please open to examine by yourself.
Thank you for reading