I think it's the death of non-chaperoned social gatherings in youth culture. Talking to the Zoomies I know, they just don't do house parties or beach parties like where I was introduced to drinking in high school, clubbing and bar hopping is expensive as fuck for college students now, and woke consent culture on campus has made frat house ragers and dorm parties damn near verboten due to fears of rape or being accused of rape.
Add to that, as others have mentioned, drinking is something us Xers and Millennials tend to make part of their personality (I'm very guilty of this), and the younger generation just doesn't want to partake in something geezers like us do.
Honestly, as much as I love beer, good on the kids. If they don't swap in weed as a crutch, they'll be ahead of the game. Vaping may be cringe and tacky as a habit, but it doesn't make you unproductive or a retard.