The i9 is their "performance at any cost, even security" chip. It's for people who want/need the absolute fastest chip and damn the torpedoes. It's so far past the optimal point on the price/performance curve that nobody sensible will be buying it unless they have a very specific need.

I'm no fan of the i9 series at all, but if you have SIMD-heavy workloads (especially anything you're willing to port to AVX-512), those CPUs actually make a lot of sense price/performance wise. It's a fairly specific niche, but not necessarily a tiny one.

It would be suicide to market it in this way. They actually made some security hardware improvements and highlight it. Sure, you could disable hyperthreading and I agree that it might be beneficial for side-channel attack protection, but it's not like Intel is officially accepts that as a valid option. At least I didn't see anything like that.