i kinda wanna see how he lives to be able to have two pcs. a high end rig aint cheap and takes some space.
is it normal for streamers to have one pc just for streaming?
If you are serious about streaming, yes. You'd be surprised how difficult it is (or was? Haven't kept up with hardware) to do a one PC game+stream setup. It's not to say impossible but your choices of games tend to be limited (to avoid overtaxing the rig) and often required good knowledge of streaming in general to even get a basic, no pixel stream going (settings, bitrate, etc etc). And this is for legit one PC setup built with the best available hardware, none of that insane "We have the power of 999,999 PCs in one case" bs. Of course, if you don't plan to game and stream but are just doing say.. chatting, podcast, review, IRL etc etc a single PC setup works fine.
Two PCs just means you no longer have to worry if your game BSOD that your entire stream also BSOD. Also gives alot more control like what Achors just mentioned. Makes troubleshooting also easier since if one device fails, you know its that device. Another upside is if you want to stream from something else (say console, at a diff venue, etc) you don't have to fuck around with your gaming rig and just bring your streaming PC.
I wouldn't say a two PC setup is insanely expensive. The last time I dabbled with live content media, you just had to make sure you have a competent GPU and CPU onboard. It's the gaming rig that often may or may not break bank.
EDIT:
Don't some people make do with a laptop? It seems manageable and he seems like a guy interested in technology so the only think that's unusual is he didn't talk about how he only has a windows account for vtubing and uses some linux fork for everything else.
Not really a powerlevel but I still have an old laptop I can use. It's not high end but it's really useful to have a backup in the event your screen breaks or hardware fails. If I streamed for a living I would 100% have 2 PC's ready to go rather than risk time off due to one of them getting fucked up, it's a work expense and even if it becomes outdated a PC will last you years. Kinda like how the penguin has 2 ISPs, which oddly enough I consider too autistic but I find her dedication endearing.
Yes, some people make do with a laptop (fine example of has just the right amount of juice to take in AV from the capture card, process it, stream it).
And thank you for pointing it out, these rigs often times CAN and WILL BE considered business expenses. If you can explain it to your accountant, they will accept it as a necessary business expense, to which then it falls on making sure the taxman understands that you do streaming AS A JOB and not some hobby (no claiming expenses on any income from a hobby, sorry moonlighters!), the taxman must begrudgingly accept it as a business expense. (something something, can claim the space you stream from as expense or something too, idr).
So, that can kinda soften the blow of getting a two PC setup sometimes.. but with its caveats ofc
EDIT2: Personal tick but I would also like to add that multiple monitors is such overkill. I can kinda get another monitor for chat, maybe another for your streaming software so you can keep an eye on all the technical stuff. But 9? Wtf are you doing? Some NSA-CIA-FBI-SEAL Team 6 shit? What? You got 9 pairs of eyes that can keep watch on all 9 monitors? And don't forget about even trying to find a way to rig that all up.