High-caste identity itself depends on subordination of low castes.

Evidence

To a low-caste man, a high-caste man can be better or worse as compared to other high-caste men. A high-caste man cannot be a good man, in so far as he must have a low caste man to distinguish him as a high-caste man. It cannot be good to a low-caste man to be conscious that there is a high-caste man above him. — Ambedkar, B R, Annihilation of Caste_ The Annotated…, 1243