Why is this, you ask? As spotted by 9to5Mac, it seems that this is because breaking your iPhone X or damaging it out of warranty will cost you a ton of money. Apple has recently updated its flat-fee repair pricing page and according to the page, a screen-only repair will cost $279 (almost a quarter of the price of the base 64GB iPhone X), while all other damages will set you back a whopping $549, which is more than half the price of the standard unit.
This means that should you drop your phone, get it wet, or damage it in whatever way when not covered by some kind of insurance plan, then prepare to pay through your nose for repairs. That being said, it should be noted that percentage-wise this seems to be similar to the repair costs for the other iPhones. For example 64GB iPhone 8 costs $699 and repairs will set you back $349.