No one said it's their only revenue. You're making up words no one said. It is unethical to consume content without accepting that ad revenue is how its covered. That's it.
Well in my belief, ads are unethical. These two views don't reconcile. And since I'm in control of my computer, I get to decide if the ads play or not.
Because if "ads are unethical" under your definition of "unethical", then I think it's totally fine for people to do "unethical" things.