(your estimate income)=(your avg hashrate)/(network hashrate)*(24*3600/blocktime)*blockrewards
Is difficulty also calculated from the variables mentioned above? Just wondering because I was expecting that difficulty is used as a variable to calculate profitability.
Not all of that variable used.
It depends on the coin itself, for every how many blocks they will retarget their difficulty. Let's say Bitcoin as an example. Bitcoin difficulty will retargeted every 2016 solved-block, with 10 minute block time, mean Bitcoin will re-targeting its difficulty every two weeks. If 2016 block solved before two weeks, means difficulty too low and will increase the difficulty.
How fast or slow block solving also related to Network Hashrate. So, difficulty related to Network Hashrate, Block Time, and time of re-targeting itself.