I'm just happy that some wanna-be-whales who charged their credit cards and made GPUs disappear from the stores, will be in trouble if the prices stay low for a little longer and might have to sell some GPUs in order to pay up their bank!
I wonder.... if you bought 50x1070ti for 750€ each a month ago, that'd be 37500€. Now those would consume about 10€ in power each I think, plus something extra for the rest of the system but for the sake of simplicity let's say 10€ power/month/card +50€ = 550€.
I have no idea what's the credit's card fees like, but I believe a 5% intrest-rate on a 12-months plan would make sense. That'd be around 3.281,25€ per month.
Based on some online calculators, they'd make 1650€ in ZEC/ETH per month (without counting tx fees for a cryptocoin to reach your bank in euros).
So adding all up,
+1650€ mined
-3280€ for the GPUs
-550€ for power consumption =
-2180€ for the first 12 months.
I know how the markets work though and I believe that the prices will go up again, but hopefuly if people overcharged themselves out of greed to buy as many GPUs as they can get their hands on, they'll start selling them now and we'll see some lower GPU prices. We're talking about a seemingly 35.8 months for ROI!
(it's actually ∞ for ROI if you count the rising diff and that new stronger cards would arrive by 35 months).
Bottom line: If you invested in crypto by buying through an exchange, just hold, you'll be fine. If you have a few GPUs that you bought in good price, worst case scenario you'll make less money that you had hoped or brake even. If you were greedy and bought more than you could handle hoping you'd pay-off through mining rewards, you're screwed!