Hundreds of thousands? For what?
Sorry to burst your bubble but they're not things I make (I'm not deadmau5 but I have a deadmau5 Pandora channel). My forte is file preparation and distribution for dozens of people to about a half-dozen channels where missing deadlines is not an option.
Not saying more cores won't finish your project quicker.
As an example, I have a client that has a wildlife video centric Youtube channel, that recently upgraded from a i7 9700K to a i9 9900K. According to his tests using HEVC, his gains were around 20% in Handbrake, coming from 8c/8t to 8c/16t . In my eyes those are diminishing returns for the money he spent. Granted that is on W10 and the extra grunt was the result of HT. But he is ok with that.
For the purposes of encoding, hyperthreaded cores are not the same as a real dedicated core. Hyperthreading works by sending dissimilar tasks through a core to take advantage of the core's unused instruction execution units. If you're doing the same task (i.e. video encoding) it's harder to see gains from simply swapping in extra hyperthread cores. If he had upgraded from a 8c/8t to a 12c/24t CPU and didn't allow hyperthreading (with everything else being equal) I'd bet that he'd have seen significantly more than a 20% delta in rendering speed.
With that said, the majority of my experience with the x264 encoder is through ffmpeg and not HandBrake (CLI version) though I note that both seem to have similar speeds encoding the same file using essentially the same options.