The mining business must be taken as an investment. By the same way as investing in other asset classes.

Good compare is the traditional stock returns which are yielding (in long term) something about 9% p.a. In mining you can reach that number easily and much more.

But do not except to receive 100% in a month. With a bit luck and for a short period of time it has been possible but annually the numbers are much much lower. This year has been a bit over 200% ROI / 100% profit p.a. (not month). I expect will end the year quite close to this number.

GPU/ASIC gap stays the same or widen a bit.

edit: Numbers