is, at its core
, nothing more or less
A gonzo journalist recognizes that the reporter cannot be separated from the story. All reporting that claims to be objective (your local newspaper, the television news, etc.) is farcical.
A story told by a reporter is necessarily filtered through his or her own perception of events, not to mention the dubious accuracy of said reporter's sources. And, ultimately, there are the extra-personal filters a reporter encounters.
Recognizing this reality, and taking what it implies to the extreme, the gonzo journalist reports on the only thing s/he can be sure of: his or her own experience.
Taking large quantities of drugs tends to make your experiences more marketable. It is not, however, a requirement.