I don't think that's generally true. As someone who was in college during the vinyl era, although I created mix tapes and taped vinyl that others owned, I never did a lot of purchasing of pre-recorded cassettes and I think my behavior was pretty common. Certainly, the "record stores" of the era carried far more vinyl than cassettes.
Fair, but didn't that change once CD players showed up in cars? Some people were certainly buying up loads of tapes (but they did wear out, so some repeats?)