but both only kill you if done to excess.

You'd think so but nope! According to WHO (and every other relevant organization), relevant risks increase from the first drop of alcohol, so while smaller amounts are less dangerous even moderate consumption will still literally kill you. Technically moderate consumption has some minor health benefits, but those are canceled out by the risks.

while the greatest risks are seen with heavy long-term use, even low alcohol consumption (defined as less than one drink per day) or moderate consumption (up to two drinks per day for men, and one drink per day for women because they absorb and metabolize it differently) can increase cancer risk. Among women, light drinkers have a four percent increased risk of[breast cancer, while moderate drinkers have a 23 percent increased risk of the disease.

Apparently alcohol kills about 170k+ people a year and causes millions of ER visits in America alone through various mechanisms (this data is an underestimate).

PS: I chose alcohol because it's the more controversial of the two, but everything I said here also applies to smoking.