New miner need answer to easy question

Hello. I will be quick, don't want to waste your time.
I'm planning to put mining rig, buy everything and start mining with 4x RTX 3060 (LHR).

By the profitability miner calculator -> whattomine-com ( not affiliate or anything similar ) they say i should expect 8.50$ pure profit/day for ETH.
This is backed with couple of other reputable sites.

If nothing major happen to the market, can i expect earn around 8.50$ every single day in next month ( i'm aware of price fluctuation on daily and monthly basis, and its all fine if profits are changing for all of miners ) or it depends, so one day i could not earn anything 0$, next day 2.33$, next day 8.56$, next day 1.12$ and so on?

I'm looking for somewhat stable income, and 8.50$ per day is more than enough for me.

Which one is correct?

Calculations are made for Etherium but im interested also in ravencoin, ergo, etherium classic, etc.
As everything i know there are a lot of variables but...
I tried with Google but didn't find my answer.

Thanks to everyone that puts time into answering question.