There was a massive portable analog audio player market before MP3 players came along. So Apple could improve on the attempts to offer a digital audio alternative. And they did. This supports what I wrote about the purpose of Apple Vision Pro. There is none. VR has forever been a solution looking for a problem.
There effectively wasn’t a tablet market before the iPad.
You also forgot ‘mp3 player’ - which was a market not created by Apple but there wasn’t really a “growing mass market” - it was niche at best.