I'm a college student and I listen to quite a bit of this "old music". In fact, my favourite bands are Yes, The Electric Light Orchestra, The Beatles, The Police, Led Zeppelin, and Supertramp. I can trace this back to my early childhood when I used to watch the trippy Yellow Submarine cartoon that featured music by The Beatles. I really developed my musical preferences in my teenage years, when I was reintroduced to The Beatles when my school band performed a medley of Sgt. Pepper's Lonely Hearts Club Band and I started absorbing everything Beatles, along with collecting all their records- I was infatuated. This spread slowly to other 60s bands- The Doors, The Jimi Hendrix Experience, The Rolling Stones...I can't really recall what happened after that for a while...
I heard some Rush on a Classic Rock station on the radio and borrowed a greatest hits compilation from one of my friends who had just picked it up because he heard them on the station too. We both went to see them play live when they came to San Diego on tour, it was the first real concert either of us had ever been to.
Around the same time, that same friend and I began listening to vinyl records on our record players (we both had one). We'd go to to the local "swap-meet" to find records, where I picked up my first ELO record for "****s and gigs", I said. It was their debut album and I was blown away (it still stands as a favourite of mine, actually). We moved from there to hitting up the local record stores, eventually finding a little shop nearby that sold records in excellent condition at a low price. We were both huge "old music" junkies by this time, so we'd pick out records from the bands we knew and loved and also sampled some of the bands we'd maybe heard once or twice somewhere but didn't know much about, like Chicago, Blue Oyster Cult, and The Moody Blues. My uncle randomly decided he'd supply me with records too, and that's how I came across my first Yes record (though I'd had some experience with them on the radio, you know- Roundabout, and maybe Starship Trooper or I've Seen All Good People once in a blue moon), which was Fragile. I was astounded by the musicianship, sophistication, and complexity that I heard, and it really kicked me into overdrive with Progressive Rock.
It feels like I've been listening to this "old music" for so long, when it's really only been about 5 or 6 years (though, to be fair, I listen to A LOT of music). And, since this seems to be the epilogue of my massive, reminiscing post, I'll just mention that the same friend that lent me the Rush album and listened to vinyl records with me happened to be quite the guitarist, and together we formed an original "alternative" Jazz-Funk-Rock band, which continues to be a lot of fun. And, yes; we're both long-hairs.
