One likes to do it oneself.
Who is "one"?
I
one of people in general
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.
Sign up to join this communityThe royalty/aristocracy of Britain are often characterised as using "one" to mean "I". This has become a rather hackneyed joke amongst comedians.
In every other case "one" is the impersonal pronoun. It is rarely used these days except in formal writing. It would sound pretentious in everyday conversation in my opinion.
Note: I use it occasionally on this website. I never use it in conversation - I would be ridiculed.
Oxford considers this usage to be that of a grammatical pronoun, and as such it conforms to the third definition in that section: “[third person singular] Used to refer to the speaker, or any person, as representing people in general”. This is in essence your second choice, “one of the people in general”.