mining is a game of luck and calculation. you need both to be profitable and since you can't control your luck , at least do your calculations right.
First of all you need to need to know these inputs in order to make a proper calculation.
1- The miner cost ( depends greatly on where you source it from and the quantity )
2- profitability of the miner based on your power cost , use this website >
www.whattomine.com or if you are lazy enough use this >
https://www.apanel.comonce you have those numbers , you need to calculate your ROI ( return of investment)
ROI = miner cost / daily profitability / 30 = ROI in months.
miner cost ( constant ) while daily probability is (variable)
depending on the mining difficulty ( how many other people are mining beside you) and the (coin price ) so your ROI can extend and can shrink widely.
most people use current statistics to determine ROI, and then people have different ROI target, to me , anything that can't ROI in 12 months going to be a loss
simply put 12 months is usually enough time for ASIC manufacturers to come up with next GEN miners that put your miner in obsolete mode.
however this is personal , some people just mine for the sake of it, and i am sure most miners will never ROI , mining last year was everyone's dream, it was so easy to ROI in 1-2 months , prices where high, difficulty was low, you buy anything , put it online and you make decent profit, however now things changed, big players came in, many things changed.
mining now is nothing different from any other business, competition and risk are at all time high. and in most cases you can' be creative to save your investments as there are some factors that are beyond your control.
I do not want to sound harsh but really if you do not have cheaper power than the Chinese miners or at least something similar (3.5 cent / 4.5 cents per kwh) then you are getting yourself in a losing war and the only thing that can save you is spike in prices, and should that happen , you are probably better of holding crypto than miners.