"pop-culture enthusiast," 1963 (in a book about the Beatles), from pop (adj.)+ -ster.
Entries linking to popster
pop adj.
"having popular appeal," 1926, of individual songs from many genres; 1954 as a noun, as genre of its own; abbreviation of popular; earlier as a shortened form of popular concert (1862), and often in the plural form pops. Pop art is recorded from 1957, said to have been in use conversationally among Independent group of artists from late 1954. Pop culture attested from 1958, short for popular culture (which is attested by 1846).
To dismiss him [Johnnie Ray] out of hand one would have to share (as I can't) that facile contempt for "pop" culture, and by implication "pop" audiences, which is the principal flaw of that ambitious new musical, "Expresso Bongo." [Kenneth Tynan, "At the Theatre," The Observer, May 11, 1958]
-ster
Old English -istre, from Proto-Germanic *-istrijon, feminine agent suffix used as the equivalent of masculine -ere (see -er (1)). Also used in Middle English to form nouns of action (meaning "a person who ...") without regard for gender.
The genderless agent noun use apparently was a broader application of the original feminine suffix, beginning in the north of England, but linguists disagree over whether this indicates female domination of weaving and baking trades, as represented in surnames such as Webster, Baxter, Brewster, etc. (though modern spinster probably carries an originally female ending).
Also compare whitester "one who bleaches cloth;" kempster (c. 1400; Halliwell has it as kembster) "woman who cleans wool." Chaucer ("Merchant's Tale") has chidester "an angry woman" (the 17c. had scoldster). Also compare Middle English shepster (late 14c.) "dressmaker, female cutter-out," literally "shapester," sleestere (mid-15c.) "murderess, female killer" ("slay-ster"). Sewster "seamstress" (Middle English seuestre, late 13c. as a surname, also used of men) is still in Jonson but was obsolete or provincial after 17c. In Modern English, the suffix has been productive in forming derivative nouns (gamester,roadster,punster, rodster "angler," etc.).