Because difficulty...

At todays diff with $0.10 elec and 2% pool fees, net profit is estimated somewhere south of $10 a day according to coinwarz.

There was a time when they made $20 a day when difficulty was lower.  If you are getting older info it may have been accurate at the time but not now.

You do understand there is a really strong likely hood diff will continue to increase for quite some time to come right?  You don't seem to grasp the relationship between diff and revenue generated.