Coin prices have plummeted lately. They may bounce up again, they may stay the same or they may continue to decline further. But mining difficulty will continue to rise. This creates a "perfect storm" of rapidly declining mining revenue. It is extremely doubtful that anyone building a rig today with electric higher than 10 cents a kw will ever get a ROI.
I'm building a rig but I am under no illusions that I will make money out of it. Would be nice but I no longer expect to. My electric is around 15 cent a kw so I am very much in the hobbyist camp. I can only envy those who live in countries with cheap electric for whom it can make long term profits.
Coins are plummeting, difficulty is rising. This looks a lot like the beginning of the end.
I pay 0.13 - 0.14 USD per kWh. I would bet my bottom dollar when most of those paying 0.09 are bowing out, I'll be in profit.