1) Give up Raid. That's just nonsense nowadays. And it won't make any read/write of your files faster in reality. I have Enterprise Optane drives, it doesn't make 3dsMax read textures even fraction of second faster and Optane is magnitude better than the sequential monstrosities with NAND :- ). You will never utilize the sequential advantage over single drive, they're already absolute over the top. Save the money, save the complexity, be more safe.
2) I have no issue with 2000W PSU :- ). But since adding second GPU is almost impossible nowadays, high-quality 1600W PSU might be better choice. That will still be overkill (but overkill is good for transient spikes and stability), but closer to ideal efficiency curve and it will be of higher quality.
3) Yes, 13900K, 7950X/7950X3D are in fact, faster for working during 3dsMax than current Threadripper/Xeons. With Threadripper/Xeons, you get the multi-threaded advantage, which is good if you also use your own PC a lot for rendering final files as well (like overnight).
Sadly Threadrippers due to PRO tag got lot more expensive, so they are the same price as upcoming Xeon-S (expect my testimonial video soon lol). A lot of money, for less improvement than you might like. If you only need single PC, buying them still makes sense. If you own studio with employees, I would buy everyone 13900K/7950X and only buy Threadrippers/Xeons/Epycs as Render-farm.
Also, you have to account for the price of components, buying 128-256GB DDR5 and 2TB of SSDs and current motherboard and PSU prices really offset some of the sting of Threadripper/Xeon build. Don't buy 3 Mainstream PCs for personal use :- ). It's either 1x Mainstream platform + 1x Enterprise platform, or just 1x Enterprise platform.
HERE COMES THE MOST IMPORTANT ADVICE :- ) Right after you build the PC, INSTALL NEW FIRMWARE for the Samsung 990 Pro. Like the first thing you will do.