Depends on the topic. That might be true of smuggling, but as a counter example, all the research on anonymity is conducted by academics and white/gray hat hackers, and openly published. Most of the people selling anonymity "guides" are scammers. You can find all the info for free, and in some cases the paid advice is dangerous. A few months ago, multiple people came on the forum and asked about increasing entry guards to 8. Apparently someone was selling a guide with that information. Yeah, you don't always get what you pay for.