Consider this thought experiment. Second postulate of SR (invariance of c) says that the speed of light is measured the same for all inertial observers regardless of their relative KE. To better understand what that means I try to imagine how would that look from a perspective of the moving light? I mean when we symmetrically inverse the postulate to the light's point of view instead of the perspective of the inercial observers. Would that mean that from the light's perspective everything with a rest mass would either fly away or getting closer with exactly speed of c and that light basically ignores their relative kinetic energies?