Taking into account the power consumed you usually (depends on the currency you mine) don't make a profit.

Actually with the recent spikes in bitcoin, it's become profitable again - for the moment. Lots of people standing up mining rigs, or dusting off their old ones.

No even at current prices anything but an ASIC will makes pennies a day while costing dollars to run. You could mine other currencies and convert to Bitcoin if the hardware is new enough, but the easiest option, NiceHash, is still offline after the massive hack