Krishna says something startlingly honest here. Even the wise act according to their inborn nature. All creatures follow the pull of their prakriti. So what good does brute-force suppression do?
This does not mean self-discipline is useless. It means that white-knuckling your way through life, fighting every impulse through sheer willpower, will eventually fail. Nature is powerful. The real work is subtler: gradually refining the inner landscape through awareness, practice, and discernment. Quick fixes and forced denial do not hold up over the long run.