The problem of mining coins with low difficulty is that these are often new coins that are not even traded on the exchange, or there is a little-known on the exchange, small trading volumes and a low price.
What makes you doubt the profitability of mining.
Not all coins make a profit this way, but you can earn some money quite well.
I strongly disagree about that, before a miner decide to mine it and he has been doing research to determine the risk that he will face it. Remember there are two choices and when you wanna mine promising coin and you should put more money to buy more rig and when you have not enough money and then your only choice to bet on the unpopular coin. But there was a lot of medium coin with enough volume these days.
How do you know which coin will be promising?
Remember how ethereum 4 years ago were selling for 1 dollar.
Is it a promising coin?
No one knows which coin will have a good price in 1 or 3 months, let alone 1 or 2 years.