What an utterly idiotic way to look at things. People don't make investments that guaranteed to lose them money, and justify it by saying, "Well the exchange rate of the USD might improve, so it's not a bad investment.
If you're going to tread on the probability of a Bitcoin exchange rate increase, buy Bitcoin. Buying mining equipment that mines at a loss, in hopes of recovering $ by exchange rate changes is as stupid as buying bulldozers at a loss to mine gold, in hopes that the cost of gold would increase. You'd be a fool to do that, instead of just buying gold in the first place.
Face it, ROI on these miners at the price we paid is TOAST. Dead. Over. Finito. Justify it to yourself however you want, but don't expect anybody to take you seriously.
While you are correct that expectig a positive BTC RoI on anything at the moment is unlikely at best, you need to look at people in general. When I was in the Navy, you could opt to have $10/$20/$50/$100/xx taken out of your paycheck monthly to be used to buy savings bonds. Since I had already been out of my own for 7 years since graduating HS at the time I enlisted, I had bills like car payments, insurance, credits cards, etc. that the average kid just out of school did not. I elected not to have money taken out. I did ask the pay clerks on average how many people DID use this and the answer was less than 10%.
If the average bitcoin miner is the same, they can't or won't take the time to invest monthly into stocks or bonds or even BTC. While I am not an average BTC miner, like most I have monthly bills, Rent, Electricity, Gas, Water, Credit Cards, Car, Insurance, Phone... the list can go on and on. Now, I can either add a new expense to the ones I have... investing in BTC monthly... or I can make a purchase and just pay a slightly higher electric bill and have the investment happen for me. Like purchasing Gold or Stocks, purchasing BTC usually involves a middle man and will cost you a % of your purchase. I never purchased gold or stocks due to this middle-man fee. It felt like I was being ripped off every single month. If I buy the equipment though, I only pay a premium once and I can ignore the added expense of my electric bill, or I can put in florescent or LED bulbs to save money to offset the added cost.
Sure, the most sensible thing to do is buy and hold BTC. But it's boring. As I said someplace else... if I really want to watch grass grow, I have a yard. But that equipment is something tangible that I can hear, feel and see. Every day the numbers change, I may make a little more or a little less, but I am making something. I can see my investment grow, not sit as a static number in a wallet that I have to refrain from using and pray that dip in price is only temporary or panic and cut my losses.
Not everyone CAN save. It's an unfortunate fact.