I agree that a very probable outcome is that the real bad drivers will, for one reason or another, keep using non-self-driving cars way longer than good drivers

I agree that a very probable outcome is that the real bad drivers will, for one reason or another, keep using non-self-driving cars way longer than good drivers. But also a good self-driving car should have faster reflexes than a good human driver, so it might mitigate anyway the damage done by a drunken driver.