Alcohol is a high energy, reactive species. Both it and its downstream metabolic products cause a host of DNA degradation: cross-linking, etc. Accumulation of this class of damage causes aging, cancer, dysfunction, and other cellular disease states.
Every nutritive food we intake, including the gaseous and reactive molecular oxygen, is reactive and damaging. Some are worse than others, but we can control what we consume.
In time, our view of many of the things we do - breathing dirty air, consuming too much alcohol, maintaining an unhealthy gut microbiomes, etc., will inform new habits.
We don't know what the lower bound of safe alcohol consumption is. Modest consumption probably increases risks, but it may be negligible against the background noise of everything else we bump into. The effects will also sum with any other bad habits an individual may have. Population studies are messy, but we do know the biochemistry.
I only had an undergraduate biochem + general chemistry degree, so I'm not "credentialed" in this space. I continue to read the literature regularly, though, because it interests me deeply. I do worry about alcohol consumption's effects on my health, even though I continue to drink kombucha and have a cocktail every now and again. It still wears on me.
We're all killing ourselves slowly through eating, breathing, and metabolizing. You can worry about it, you can disregard it, you can make small changes, etc. We're all dying, though.