I reject the thinking that "people are going to do what they want" and we are helpless to influence their behavior so we should just accept whatever they are doing no questions asked and work around it with public policy if it causes a problem. The reason I reject it is because I would argue "what people want to do" does not spontaneously arise in their minds, but rather is influenced by popular culture, marketing, and more.
Take alcohol for example. You might say "you can't prevent people from drinking, look at Prohibition, it was a complete failure, don't even try", and in a certain sense you are right. You can't prevent all people from drinking.
However, you can prevent many people from drinking (or at least, reduce the total amount of drinking to more moderate levels) by:
- Not glorifying alcohol via pop culture and movies (especially American binge drinking at age 21)
- Restrict/regulate alcohol advertisements and marketing to reduce the influence of "drinking = happiness" messaging
- etc.
Or, stated in other terms, you can exacerbate your country's alcohol-related issues by glorifying alcohol and enshrining it in popular culture.
In the same vein, maybe we wouldn't have as big of a problem if we didn't glorify casual sex encounters so much in our media. If popular media/culture instead glorified things like self-restraint, commitment, etc, I'm sure some % of people would be influenced.