Due to how the difficulty system works, the real-world price of the reward for mining will always be equivalent to the cheapest energy price in the world. If the price suddenly increases, more miners get in, which pushes the difficulty up and now you have to expend more energy for the same reward - similarly if the price drops, miners who can no longer make a profit go offline, lowering the difficulty - in the end it's an equilibrium.

I don't think it was ever profitable unless your energy prices can compete with what industrial-scale miners get in favourable locations (right next to a power plant in an area with too much surplus power, etc).