The most important thing not addressed here is demand. Last I checked (granted, this was a while ago) it simply wasnt there- Meaning if you built this rig you might only be able to rent out a small part of it.

If this has changed I would be interested in hearing about it-

One other thing I am not understanding is how this makes financial sense, even if the demand is there. If I am buying a rig for 4500 bucks to get 200TB, making "570 a year in profit" is nowhere near exciting enough. Practically any other use pays more. Renting a dedicated server for a game, web hosting, hell even GPU mining makes more.

(a single 1080ti can do about 1$ a day in gross revenue on grin/eth/etc - which can be had used for ~400 bucks- Or you can get a p102 which is the mining card version with no display output for 250 bucks) - Payback with power costs/etc.. well below the 10 year threshold of siacoin)

Now where it might be interesting (IF there is demand), is just adding harddrives to an existing infrastructure already in place. So if you are a GPU miner and have 1000 rigs already in place, just adding a single 4TB harddrive to each machine might not be too bad- They go for about $50 each used and according to this, will pay back $8 a month with minimal extra costs