if its free electricity mine all you can get
Not really, it depends on the mining gear that you purchase. For example, if you had a PC you are currently using, and then moved that to a 24/7 mining setup, it'll be much more profitable then buying new antiminer gear, etc.
If you have free electricity or free power source mining for you is profitable and it depends on what mining machine you have because if you mine coins with GPU the ROI will take years before you reach the ROI. But if you are mining with ASIC miner I think you can reach the ROI fast.
You don't need a deep knowledge of Hardware/software. It is enough if you know how to maintain your miners or how to clean them and knowledge to set up the pool is enough.
ASIC miners do cost thousands of dollars, but GPU's will eventually wear down from your constant mining. I'd personally look to repurposing your old PC equipment, or doing the calculations and buying a new antiminer or 2.
If you have free electricity or free power source mining for you is profitable and it depends on what mining machine you have because if you mine coins with GPU the ROI will take years before you reach the ROI. But if you are mining with ASIC miner I think you can reach the ROI fast.
if we exclude bitcoin from the list then it depends on timing. there are years (like this year) that altcoins are dumping hard and everyone loses money even miners so they will have a much harder time reaching profit let alone ROI. of course with no electricity cost it will be better but not by a lot.
then there are years when we have lots of altcoin pumps like 2017 or 2013,... and mining coins, specially the GPU coins (since they are pumped a lot more) is more profitable than coins that are big enough to have an ASIC.
Ah, this is well-said mate! I'd personally recommend picking an altcoin you are personally interested in, and then with a bit of luck, and some price rising, it'll be much more worthwhile to mine it, then BTC.