I don't know how you're running the numbers, but they're wrong. First of all the ROI of an S9 is not anywhere near as long as 400 days, even with bitcoin doing so poorly recently, so that says something right there, that it can keep being profitable even in this environment. Second of all - assuming the difficulty keeps rising and the price of bitcoin keeps falling - yes, the S9 would not make a good investment. However the truth of the matter is that you can't see the future any more or less than the rest of us. You don't know if the price of bitcoin will keep falling, or if it will rise, or what the difficulty will do, etc. If you believe in bitcoin and believe it will make a comeback (which history tells us it will), then you don't base your numbers off today, but what you expect them to be in the future, especially with something as volatile as bitcoin.
This is wishful thinking.
BTC value cannot be forecast but you can make some pretty good predictions about total network hashrate and difficulty, I’ve shared mine on various occasions in this thread and even the best case scenarios don’t show an S9 to be a good investment currently, worst case scenario shows the S9 to be money down the drain.
It’s been over a month since I built those forecast and so far the total network hashrate is growing even faster than my original worst case scenario. That should tell you something.
Anyway, you can find the work a few pages back in this thread, check it out.
I dont know what hashrate chart are u using, the one im watching hashrate is falling
https://www.coinwarz.com/network-hashrate-charts/bitcoin-network-hashrate-chart
Difficulty retarget chart
Date (24h UTC) Feb 7th, 01:49 -
Remaining 5 hours, 25 minutes (37 blk) -
Change +10.16%
Happy mining