There were a couple things Apple had in their favor but it certainly didn't take 10 years for folks to catch up. They mostly one because they captured people's hearts and minds.

The key things Apple did right was a high speed connection and owning their software. The Creative Nomad Jukebox used the same HDD as the iPod and beat Apple to market by a year, but Creative didn't own the software. The iRiver H series of players showed up around 2004 and were comparable to iPods in terms of quality and capability, though their aesthetic wasn't polished minimalism. Their UI wasn't as good but it was still very good. Their crux was Windows and Mac support wasn't great. I had an iRiver in 2007 and was running an opensource (rockbox?) firmware to get around some of those issues.

Apple has always been good at innovating around the problem which is usually the UI or software at large. This comes in part because of their vertical integration and being able to make minor tweaks to other parts of the ecosystem (e.g. desktop OS) to dramatically improve the experience of their product. The iPods are another great example where they made minor tweaks to iOS Bluetooth that magically made the experience of using wireless headphones dramatically better.

You synced music by manually managing folders on the device. All my non technical friends were horrified by it. They didn’t have neatly organised mp3 libraries. For all of iTunes’ problems, being able to plug in a cable and hit the big “Sync” button was really simple and convenient.

The Creative Nomad Jukebox used a normal laptop 2.5" drive. The iPod used a new 1.8" drive from Toshiba that Apple bought up the whole initial run of. That's why the iPod was smaller and more pocketable, the Jukebox was more the size of a CD player.