It's clear in hindsight, but a high school student with little life experience who sees a long text post with hundreds of upvotes and a couple awards can be an easy mark.

It's especially difficult because there is actually good advice mixed with the bad and unsubstantiated. I've taken good advice from certain comments (e.g. that led to the discovery of open courseware and actually quality resources on physical exercise programs).

But part of maturity is learning to be skeptical of advice independent of upvotes, so one can get the good advice while avoiding getting mislead. To answer quick questions, I try to search for articles from reputable newspapers first (to see if a verified expert interviewed by a journalist is quoted at length) and possibly HN's archives via Googling with site:news.ycombinator.com. For more complex questions and topics, I try to find book recommendations from Reddit that were written by academics or low-profile experts over influencers, and then reading about the topic at length (e.g. it's usually far better to learn about big social problems if curious through well-sourced books, versus any hot takes online, regardless of the popularity of these hot takes).