[fennecfoxen]

I dunno, plenty of addicted people recognize their behavior is destructive and they care a medium amount about that. They just care about getting the fix more: human brains have a multiplicity of decision-making agents, and the long-term self-control ones don't always win, especially where these types of addictive agents are involved, but also when they're in the sort of life situations which make quick fixes (like de-stressing yourself by smoking) attractive.