Well the core of the atom has a positive net charge . For atoms with many electrons there is a negative electron cloud . How do valence electrons even exist? The electron cloud is closer to the orbital of the valence electron so they repel it more than the nucleus attracts it . *Where I mean electron cloud I mean all the subshells before the valence electron.
If you don't include the valence electrons, the electron cloud has less number of electrons than the number of protons in the nucleus (a (non-bonded, non-ionised) atom is electrically neutral).
The net positive charge is greater than the net negative charge if you remove the valence electrons. Even though part of the electron cloud is closer, the electron cloud surrounds the nucleus symmetrically and so equal part of it is also further away than the nucleus. It effectively acts as if it's charge were concentrated at the center for the most part. In other words, the net electric charge for an atom, with, say, 2 valence electrons, would be +2 without the valence shell. So there is flux directing the valence electrons towards the nucleus (remember that the electric flux depends only on the net charge enclosed, not the distribution of charge)