There’s part of it but also anecdotally a lot of us are aware that alcohol in pretty much any quality has negative effects and therefore don’t drink at all. There’s a lot less pressure to drink than in expect there was for other generations, it’s pretty normal for me to meet other people who prefer not to drink.

Drug use, and especially problematic drug use, has low price elasticity and the US is a relatively high-income country. The cost of living is almost certainly a negligible factor in the decline of alcohol consumption.

Although most of the gains have gone to top earners, US real median household income has trended slightly upwards over time and is not "way [down]."

Moreover, high-income European countries where even fewer people are budget-constrained when it comes to drug use have also seen dramatic declines in alcohol consumption.