I'm glad you agree that if a child happens to be born to parents who aren't very good at parenting, they deserve to suffer. Basically if a child's parents smoke around them and give them lung cancer, all we should do is yell at them and moan on the internet, not actually do anything (via the government) to prevent it.
Nothing you've said contradicts that you think the government should not forbid children from buying alcohol.
Social media appears to be more harmful to a child than low quantities of alcohol, but less harmful than lung cancer.
I recommend you studying some history, especially that of Germany since 1920 till 1945, to help yourself part with the illusion that the government's overreaching care has anything to do with actual care, and to finally grok the essense of the saying:
Nothing you've said contradicts that you think the government should not forbid children from buying alcohol.
Social media appears to be more harmful to a child than low quantities of alcohol, but less harmful than lung cancer.