With free electricity, it definitely can be profitable.
With paid electricity, things look a little different, because your profits are a lot smaller AND your equipment gets old/outdated.
With every coin that is being mined out there, the next one requires more power to be mined. That's why I prefer to stay out of such investment when I know that in X amount of time, my miner will mine less value than it consumes.
With free electricity, we can assume that you make $3 per day. As time goes, you will make less and less every day(assuming you mine the exact same coin AND its price doesn't move).
Of course, you can always mine different coins, but it requires constant research on which coin is the most profitable to be mined right now.
Even though the crypto market is not as volatile as it used to be, it's still pretty risky and prices jump both up and down a lot.
Good luck!