Some bud tenders I've spoke to say that the ~30% you can find now is basically the max feasible. A high potency weed just means that you have to inhale less burning plant matter. Most adult use just involves way fewer hits than someone would have in the 70s. You can also find much lower potency strains for cheap. I imagine this is state by state though.

Everclear has existed forever, and even dumb college kids understand drinking an entire bottle would be stupid. We still haven't had teens or adults dying from cannabis overdose, even though you can go find stupid videos of people with nothing better to do smoking a whole gram of extract in a couple minutes. There has been at least one infant dying from cannabis exposure though. In babies it seems it can depress breathing to the point of suffocation.