Most forms of mining take investment at this point.  To mine BTC it's going to take an investment in a asic.  Ether is possible you could do on a regular PC if it was set up for gaming and had nice card, most are not going to be this though. So most will be investments.

But many are building PC rigs to mine Ether so it can be done, and is being done.   And profit is there if done right.