That's not necessarily true, assuming you believe the value of what you're mining will at some point in the future be worth more than it is now. I mined some Ethereum earlier in the year, and was making around $6 AUD a day.
I stopped as I was unhappy with the effects of proof of work on electricity supply and the wear on my GPU, but the amount I mined at current market price is worth around 3x that, making it quite a bit more profitable.
Of course, if you believe the value will increase at some future point you're most likely better off just buying the coin and hodling it :)