OK. If you were to write, "The original fan loses nothing, but gains the world.", that would be correct. If you replace "the original fan" with "you", you are moving from third person to second person, and therefore the verb form changes from "loses" and "gains" to "lose" and "gain".
Now, in your sentence, you write, "You, the original fan, loses nothing -- but gains the world." A sentence can only have one subject, and in this sentence, the subject is "you". "The original fan" is a descriptive clause that refers to the subject, "you", and so the sentence should read, "You, the original fan, lose nothing -- but gain the world."
Hope that's helpful. Thanks for starting a new thread. You moderators rock!
BFK is a Judge.
A Nazi. Grammar Nazi, that is.
Guilty as charged, gentlemen.