I had been using quite a few MP3 players before the iPod but the iPod was the first device that brought together high capacity with very good usability. A very similar thing happened with the iPhone. There were smart cellphones with all the features before but the iPhone was the first to combine everything into an elegant package. I think that always was the real strength of Apple starting from the Apple II: wrapping everything together into a really nice package.
I've only ever paid my own money for one Apple product, and it was an iPod. Back when they came out they weren't as great as they later became, but the hard-drive was a significant advantage.
Back before I had an iPod I had something with flash-memory, holding a couple of hours of music at the most. Having a drive meant I had days worth of music in my pocket, more than I needed for a train/gym session, but a significant upgrade for sure.
