"All these people that can't afford to take their family to watch City play Dippers/Rags/Arsenal etc , why didn't they take advantage of cheap tickets vs Palace and fill the stadium?"
They likely do.
It's the plastic whoppers and football tourists who aren't interested in an early round unglamorous league cup tie, the type that won't mind paying through the nose to attend a one off 'glamorous' league fixture against a top four side though.
They're the type who create this artificial demand for tickets which the club can exploit to charge actual blues much more.
I genuinely feel sorry for those that can't accommodate a season ticket due to work/family/cost, and have to make do attending individual league fixtures.
They're paying through the fucking nose because the club is exploiting an increased ticket demand from plastics and football tourists.