First part I'll agree, how can I not? Beer Goggles anyone? However by saying alcohol and 'drugs' you're casting a rather wide net, and I'm fairly certain that considering every conceivable 'drug' on the planet not all of them will effect a persons ability to make rational choices. Does aspirin effect your ability to decide which clothes to put on? Etc.
Your second part is just subjective conjecture unless it said "and drive". It wasn't dumb that this person did the drugs, it was dumb that he did them and drove his car.