I'm not remotely surprised young people are drinking less alcohol - or at least, they don't think it's the height of cool.
I grew up in the 90s and drinking - not just drinking but getting wasted, off your head, trashed, was really pushed on us as glamorous and even sophisticated. In retrospect that was all rather messed-up - just as much as previous generations being sold cigarettes as glamorous and sophisticated was.
An attitudinal shift isn't the same as a behavioural one. No one in my generation thought smoking was cool. A lot of my friends still smoked, because they liked it - but they didn't think it was cool. But in my early 20s almost everyone fell into the trap of thinking getting drunk was cool.
Getting drunk was fun for sure, can still be fun and I'm certainly not going to be teetotal any time soon. Love a nice glass of wine. But the 90s/00s cultural view of alcohol wasn't healthy, and I'm not surprised young people think "ugh, no" when they see their parents and their parents' generation behave in unedifying alcohol-influenced ways. I saw some unfit, red-faced 50-year-old men stumbling out of a pub at 11pm the other night, absolutely unable to control their bodies, one of them vomiting, and... I tried not to judge as I'm no stranger to that state but I thought, god, no wonder their kids think this sort of behaviour is uncool.
Maybe like I thought about my parents' friends who reeked of cigarette smoke, tbh.
Having said all that obviously plenty of young people still drink. They just seem to have a healthier attitude to it than we did.