Even the least patronage VB would partially fillup during Festival season, while SL & Gen coaches will make losses even when fully occupied, so comparison is not valid.
Few VB trains just need change in Timings or run on a different route designed by Railfans, while the fares of MAHAMANA & Amrit Bharat prove that People are willing and can easily pay a little more for these Services, now just Political will is needed to raise the Fares, these 2 classes can never be removed.