I was trying to play 1440p at 144hz while have minimal frame loss while streamingUnless you plan on using some real heavy threaded apps, I wouldn't bother with the threadripper. All around, it's going to cost you quite a bit more than the 2700X setup. I'm not knocking threadrippers, its just for what you plan to do, its way overkill, as the motherboard and memory are going to cost you a lot. The 2700X will stream just perfectly fine.
Is it a similar situation If I get i9 9900k?A 2700(X) should be fine for that. Keep in mind that in addition to spending a couple hundred dollars extra on the 2920X, you'd also be spending twice as much on a x399 motherboard.