Ethanol, drinking alcohol, is a poison (and it makes you stupid, too).
It worst long-term toxic effects are to liver cells (actually you can measure chemical/enzyme leakage from damaged cells after just a drink or two) and brain/nerve cells.
Some of the earliest, and lower dose, effects of alcohol are on the eyes. First affected are the papillary muscles that allow you to constrict your pupils in response to bright lights (making them tolerable). With these muscles paralyzed sudden bright lights, like oncoming headlights, cause you to look away or cover your eyes. Doing that can cause you to crash your car, possibly killing yourself or someone else.
As more alcohol is consumed and absorbed into your body the next set of eye muscles affected are the muscles that allow you to see one image with 2 eyes. Your vision then becomes double. You see 2 lines on the side of the road. Which one is the real line? Guess wrong and you are off the road, crashing your car. There are too many lines in the center of the road. Which is the right set? Guess wrong and you crash into (and/or “clip”) on-coming traffic. These crash scenarios can result in death(s).
More alcohol in your system? Realization may kick in that you are drunk (and really stupid) so you decide to follow something home, trying to get there safely. Those taillights ahead, something to follow, but if it’s a parked car you’ve got yourself a crash (yes a parked car can kill). Maybe you can follow those bright lights ahead, bad choice that is on-coming traffic. These things happen; this sort of “reasoning” can/does occur in an alcohol befuddled mind.
Don’t drink and drive. Don’t ride with someone who has been drinking. Think, make good choices, and don’t take chances.