I continue to maintain that thinking of mining in terms of ROI on equipment costs is only one way of thinking about mining for money. As I have said elsewhere mining rigs are tools like mechanic, plumbing, electrician tools. In order to do your job and EARN money you need certain tools. Mechanics, plumbers, electricians, etc. need their tools upfront in order to work and earn income. The cost of tools is simply the cost of doing their particular job and they do not think in terms of ROI on a wrench or a pair of plyers (unless the tool is some major capital asset). They will, of course, for tax purposes, "write" the tools off as an expense but that is purely a tax issue.

Every BTC I earn mining is converted to $$ and is spendable income. I am not interested in "investing" per se except in the broadest sense of investing in the BTC economy. The only mining expense I care about is the cost of electricity which is a fixed utility cost for living. My miners are not really either depreciated or appreciated in their initial value although in truth the value of my mining equipment may go up as BTC prices rise but that is only if I sell my rigs. Additionally, as BTC drops in value relative to $$, my mining equipment (viewed as replacement cost) can, and has, gone down. I buy my rigs when that happens.

I have noticed that in some of the BTC mining calculators that the cost of the mining rigs is used relative to expected BTC earnings over x time. Yet, those calculators never amortize the cost of the machines and that is a flaw. If one is concerned about ROI, then the rigs must be amortized over time, the value simply should not stay the same over x amount of time. That is just a normal "business" accounting practice. But, then again, since I have a different philosophical approach to mining, I could not care less about ROI or amortizing the cost of the machines. As long as they continue to work as a tool, they are are earning.

I make/create between $800-$1500 a month mining. That is money I did not have before and all I do is sit on my butt and check that the units are running properly 2-3 times a day. My machines are paid for out of disposable cash I chose to spend on them. If earning money is your goal, money you did not have before, and all you do is sit there then do it and don't worry about ROI. If you are interested in thinking of mining as an investment, then knock your socks off but you are better off buying stocks and earning dividends. In the mean time I am spending my easily-earned money and I have long ago considered the money spent on the rigs as gone.