Adblock – Is it moral to use it?

Okay, I’m faced with a dilemma.
As a web developer, I hate adblock. I think that it’s a profit-killing-evil-contraption. However, as a web user, I find that adblock is a great thing which can save me the needless trouble of looking at sites that are plastered to the knees with advertisments.
I ask, is it truly moral to use adblock? For one, you’re stopping people from earning hard-earned money from their website and it could effectively be classified as stealing.
However, on the other hand, advertisments are the scourge of the internet – as they deface many websites and the flashing colours of them could drive a person mad.
What do you guys think?
Ps: Some websites have gone as far as blocking Firefox entirely to stop adblockers.

Original post by Tobias