This is just another case of the 'Why should I improve first' trend.
To most people I've asked why they drive on high-beams (this includes relatives, drivers, classmates) their response is always the same "This is Delhi, until you blind the oncoming/leading driver by your lights he won't give you the space to move on". I find this reasoning utter ********.
They say even if they stop, the others will continue; and I got to admit sometimes in extremely bad situations this logic does make sense.
You should have responded by saying, "It's something called 'CIVILIZED DRIVING', perhaps you're not aware of it".
Further you could explain to them "If they behave Un-civilized, we should not!"