Those S19 and future S19++, pro and variants are going to make almost imposible produce money with old miners, even with S17/T17 units.
You need to always be very near the most efficient gears, if you don't invest a certain portion of your profit to re-position yourself in a better place, eventually you will be left out, this is why the duration to ROI is crucial, also the timing is very important, many people I know ( including a few in this forum) bought those latest batches of T17/T17+ for nearly $800 plus shipping, that is what I call a terrible business plan.
If you bought a T17 58TH for $817, and paid 100-200 for shipping say you paid $1000 in total so unless you have FREE power, you will simply NEVER ROI.
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.ibb.co%2Fssrqzzc%2FT17.png&t=664&c=iGIwJQ8r0n6ppA)
Even with 2 cents per Khw, you will still need over 10 months to ROI, and this is the rainbow scenario where difficulty doesn't go any higher, price doesn't go any lower and your gears don't die on you.
With that being said, after a second thought on the situation, I strongly believe that difficulty has most likely hit the top, for now, starting from the next epoch my guess is that we start consolidating to the downside for a few months (unlike I thought a while earlier for many reasons which I will talk about in the near future), the correction won't be major so if you have an S9 and pay 5 cents per Khw, it's impossible for you to become profitable again, however, the adjustment will be a small push in profit, meanwhile, I wouldn't buy any mining gear at these current prices.