One of the main benefits of owning an iPhone in general and iPhone X in particular is that it comes with great hardware and software that will be supported for years to come. When you buy an iPhone you know that it will benefit you in the future. You know that you are going to get frequent updates, new great features (ARKit is a good example) and it's a part of a larger ecosystem that works seamlessly and flawlessly with all its supported devices.
When I buy an Android device, I feel it's already outdated after a few months, watching all newly released Android smartphones. In some ways it's great that Apple doesn't release a wide range of devices and it focuses on making sure you get the best software that will work fluently with the hardware. I remember Steven Jobs talking about it, saying that one of the main advantages of owning an Apple mobile device is that both the software and hardware are designed by Apple. It doesn't mean that Apple makes all the hardware, of course not, but you are producing proprietary hardware that was made to work perfectly with the accompanied software. The hardware is optimized to support the software features. This is why many people prefer picking and iPhone over Android devices, to enjoy a better user experience, super smooth and responsive UI interaction and knowing that their device will continue to work like that for years to come.
This is why the iPhone X like other iPhones keeps a higher value compared to an Android device and you can still sell it in 2nd hand for a good price before upgrading.
The iPhone X will obviously follow the same principles, offering users great hardware and software that will be supported for years to come and superb user experience that Apple mobile devices are known for.