Theft? Of course it's theft, if I reduce to what is happening - you're using their services for free with no compensation. That is the definition of theft.

I would agree with you it's ok if there was no way to _otherwise_ pay for the service. If they push a only ads-supported version, and I have no choice but see ads, and I don't consent to the impact of ads on my brain, it makes a case for blocking ads being ethically correct.

But since there is a choice on how to pay, I find reasoning is no longer ethically right. You can choice to pay with your attention and brain, or to pay with hard cold cash, so the argument of ads being shoved down your brain no longer holds. You can choose to not see ads and pay for the service, and you chose to steal.

And you can make the argument that stealing is ok since you steal from the bad guys, but then you don't get to complain when others may steal from you - we're all "the bad guy" for somebody else