There’s a lot of rough calculations here, I’m just sounding out something in principle.
Assuming i can build a plotter that can plot 12TiB/bay for $5k
And XCH is currently worth $80, so that $5k buys me approx 62 XCH
And negating electricity costs and second had resale values for hardware.
Why would i bother spending money on a Plotter and disks when i can just buy the XCH?
Need more information to finish that comparison, Plot 12tb a day up to what max capacity would $5k get you?
Assuming you can get 100tb for $5k then 100tb would make you 62 XCH in a pool in about 7 years (with todays payout of 0.0243)
200tb in 3.5 years
300tb in 2.3 years and so on.
You should be able to do the math. (Those calcs are not assuming any 0.25 blocks you may hit in those time periods that will reduce the time)
So if it’s 100tb, then buying 62 XCH makes more sense than plotting/farming, but assuming you can get 300tb for that price than possibly that makes more sense from the fact that you would get to farm more after that period of time.
All depends on your time horizon for the investment, how much you Believe in the project. Most people can not answer that question for you, you would need to decide.
In this example the $5k was just for the plotter.
You would have to add on a 14Tb drive each day with the hardware to then host the drive.
It’s more ‘fun’ to plot and host I guess.
Also you’re right, you would have the plots for life.
Maybe it’s worth buying up XCH while it only $80 if you think it would then get to Bitcoin price level.
Bitcoin for me, is like Gold Bullion but Chia may well be the next global currency.
Anyway I digress
Was just doing some rough maths.
In the current market condition it doesn’t make sense to invest in plotting/farmer hardware indeed.
I do both 
P.S no need to shell out $5000 for plotter HW, any old enterprise server can be had for no less than $500 and can make plots in less than 30 minutes.
A good question that plot <> buy! I was thinking of getting more disk and plotting, then thought of just buying the XCH that $$ would represent. Tempted, but decided on neither right now as I have ~.5PiB already. As mentioned, simply buying XCH is a one off deal. Any appreciation is in the price. Plots are forever, and they can make some (new) money well into the (unknown) future themselves, regardless of XCH pricing. Both are investments of a sort.
That article you mention says a that TR can do 14TB a day. But the system cost is dear. I bought a ThreadRipper too, a TR Pro 3955WX w/only 16 core. Surprise! I can fill ~1/2 a 14TB a day, half what a 3970X can do (max so far 68 plots/day). Much less $$, though. TR lets you decide, for example, load up on memory (up to 512GB) or lots of nvme SSDs (all PCI-E 4.0). These luxuries are impossible with a desktop Ryzen. I could put 10 PCI-E 4.0 ssds in mine if I wanted and still have PCI-E 4.0 slots left, for example. Expansion unlimited (almost).
Given the market now, Lenovo TR P620 TRs are hardly any different in price than higher end Ryzen PCs. Even Ebay has them. And they are quiet, compact, reliable and built like a tank. In summary, these days, I’d say the best reasons for plotting over buying, if you just want to have some XCH:
Remember, whatever you do, always have fun and good luck!
Your saddling the horse upside down. That plotter for 5000$ is probably more for a petabyte farm.
I am plotting with a ryzen 5 3600 (~100 bucks). + 16 gb ram, mainboard and 2 500gb nvme drives which I scraped from old company Laptops going to junk.
Eventhough I dont even use all cores of the processor, I am plotting 18 TB drives faster than I can buy and implement new ones. Not to mention of the structural challenges when the system grows…
I think a 19 tb harddrive is full in 3-4 days.
It’s not about the newest, most expensive, quickest hardware for plotting. It’s about the most efficient allocation of your money. You can have some 20*18 tb drives totalling ~350 TiB ofr 5000.
Probably have some old computer anyways which could do plotting and hook up these drives.
Another factor is a psycological one.
One may enjoy buying the chias and having them on his account. He might not be too interested in fiddling around forever and so on. On the other hand, he must have a very cool mind if the price is fluctuating. For instance now when the prices went down. I doubt that many people have the mind to watch their capital scrumble down when pricess fall. For instance, say you purchased xch for 5000$@80. Makes 62.5 xch.
Those 62.5 xch are currently woth 4312@69.
In the mean time, my Farm sits there and farms chia for me. My value is going up in contrast. The prices go down, some farmers quit (because they bought way overpriced hardware from all that marketing) and the xch rewards for farming are going up…
well I find 1 ssd per 3-4 cores plenty.