You’re totally in the right for worrying about this sort of thinking. The truth is, our technology is not quite there yet and you can still get a DUI in a self-driving vehicle.
No cars available for sale in the United States are completely self-driving. Although the vehicles on the consumer market may appear to be self-driving, they are simply not reliable enough or technologically advanced enough that they can truly drive on their own without human intervention.
Essentially, if you are at the wheel of a self-driving car, you have to remain alert, clear-thinking, and be ready to take control of the vehicle if anything goes wrong. Sorry to break it to your friend, but you are none of those things while intoxicated.