But it is harming someone else in a way, they only want you to read it if you pay for it, there will still be bandwidth costs to cover for people who bypass the paywall, some might argue that in some paywalls, the content is already sent to your browser anyway but that's a whole different story.
It's the same argument for piracy, "if I make a copy, I'm not taking away the original, so I'm not stealing", which is just a lie to tell ourselves to feel a bit better at the end of the day.