For me, I'm not in a position to pay and likely never will, therefore I'm not 'lost revenue'
If I live next to you and I discover that I can see a member of your family when they are getting undressed, are you suggesting it would be ethical to repeated watch or even record them in the nude? What if I shared those recording with others? Do you still feel that is ethical behavior?
I feel I shouldn't have to pay for this quote.
Also, you have my sypmpathy for any way that copyright culture may have warped your understanding.
I understand that explicitly as part of my participation here.
As such, I understand you are free to quote me without compensating me and doing so is ethical.
If however, this was my site and I decided to charge people for my wisdom then yes I would expect you to pay for it like everyone else
If you found a way to get it for free I would probably be unwilling and unable to stop you from stealing it and it would be unethical for you to do so.
Wanting something does not justify taking it from someone only willing to sell it.
Just as ignoring GPL requirements is unethical just because one feels that they are inconvenient (legalities aside as we are talking about ethics)
There is a completely different question around the ethics of charging for something like information but as I say that is a different question.
Put a second way, would it be unethical to derive a work from a gpl source and simply use whatever licence you wanted because you did not agree with the gpl requirements?