Im always amused by this line of thought, should we make alcohol illegal then and ban advertising it on tv? What about soda with too much sugar? Should we, perhaps, ban everything which is addictive and causes any harm?
But note I didn’t present the “people want to do it” argument. My view is things should be balanced between their antisocial risks and their prosocial value.
IMO yes there should be extremely high taxes on high-sugar concentration foods and beverages, and probably additional impediments to their advertising. We have alternative sweeteners that do not destroy the financial viability of our healthcare system, and we should tilt the tables in their favor. High antisocial risks, low prosocial benefits compared to readily available alternatives.
Alcohol is dicier as there is a real prosocial value to it that’s non-trivial to replace, but it too should probably be taxed more aggressively as we know that small tax increases disproportionately affect the most problematic consumers of alcohol.
Note how this argument isn’t “people want to do it therefore it should be allowed?” Or “people can be harmed by it therefore it should be disallowed?”
Prohibition has costs of its own: black markets, organised crime, unsafe products, enforcement expenses and incarceration.
You acknowledge that alcohol has social benefits, but apparently heroin doesnt. Why? Because alcohol facilitates socialisation? Because its culturally accepted? Who gets to determine the "prosocial value" of an activity? Almost any unhealthy behavior can be framed as a societal cost.
Theres an enormous amount of subjectivity here. Some people genuinely enjoy recreational drug use. Others enjoy gambling, despite knowing they will probably lose money.
You are arguing that the state should determine which activities are permissible based on their net social utility. Im arguing that danger alone should not give the state a right to prohibit consenting adults from engaging in any activity. Individual autonomy has value in itself, including the freedom to make decisions that are objectively bad for oneself.