Regardless of what people said or are saying now, the main difference is that people that bought the initial iPhone loved it and used it all the time. Most Vision Pro owners stopped using it 2-3 weeks after purchase.

The iphone built on existing product categories with product-market fit: PDAs, cellphones, MP3 players, smartphones. The path to improve the initial product was clear. There was a clear target.

Vision Pro launches in an unproven market (VR/AR) with only a handful of games with significant adoption that AVP can't run as well as competitors due to lack of controllers (e.g Beat Saber experience would be worse due to higher latency of hand tracking). Path to improve the product is uncertain because the target market is not clear yet.

I both bought iPhone and Vision Pro on day one. And my enthusiasm and engagement with each product are completely different.