Do you guys know a lot about building PCs? It's legitimately not that difficult. Watch a few tutorials on youtube on how to find parts, use PCPartpicker, and assemble the PC. Again, youtube has so many tutorials on PC building, and while it seems daunting to start doing it, it's honestly easy and fun. Not to mention that it is considerably cheaper to build than to buy an already prebuilt.
Now, we know that lots of the objects are going to be streamed, or at least I heard. That is something like GeForce Now which uses the cloud to play games. Then, they will jump out of their socks to try to make the game optimized for mid-performance PCs, that's for sure (or at least I really hope).
Yet still, we do not know about the specs we will need. We know that the demo machines at the preview event had 2080s, but the older graphics cards will still have plenty of juice left in them, so don't fret if you have a midline gaming rig. I would go as far to say that maybe decent gaming laptops will be able to run it.
Building a PC is cheaper and more fun and engaging than buying a prebuilt. Microsoft will try hard to optimize the sim as much as possible. There will be cloud streaming. We still don't know if we will need a beast PC to run the sim, which I am expecting we won't.