Hmm. The marginal cost of one more person sneaking into a concert audience is essentially $0. However, I bet YouTube for instance pays an eye-watering sum of money every year serving video to people with ad-blockers. (and by extension, the creators suffer from this too).

Ok is pretty undefined here so sure.

There's an implied issue here that intangible transgressions tend to do tangible harm that is so serious, it needs rectification. I think people accept this notion without worthwhile evidence.

If one must sneak in or otherwise subvert the intentions of the provider then, it is unethical and the sneaker is aware that it is.

The question of tangible harm and restitution (if any) for that harm is a question separate from ethics.

A notion that harm is disconnected from ethics is an interesting one.