The main factors making mining attractive are :
- The coin's value
- The mining difficulty
- The price of electricity
- The price of the required hardware
- The mining fees
The higher the coin's value the higher the miner is rewarded. The less difficult it is, will likely result in more coins. Some countries have almost free electricity which makes mining much cheaper. There's also the initial investment, which is the required hardware for mining. Mining fees also help increase mining's profitability.
When mining a coin becomes attractive more miners will come which would result in more CPU power which gets corrected by a higher difficulty. If suddenly half the mining power was to disappear, we would see a difficulty adjustment.
Should the transaction fees be one of the factors as well? It's one of the source of profits for miners, if I'm not wrong. – user781486 – 2017-12-23T00:41:57.917
Yes that is indeed correct I will edit my post – Cedric Martens – 2017-12-23T00:50:27.850