Every now and then I end up on a PC that doesn't have adblocking enabled and I remember what a goddamn mess the web is in its natural form, adverts flashing all over the place. Fuck that. I deprive people of 0.0001 cents per page view, and I sleep like a baby at night. What a bastard.
Yes, I am selfish, and I don't have any problems admitting it. I'm a selfish greedy asshole. Everyone is, but some can hide it better than others, and some even manage to fool themselves. I like the concept of donations. If something's useful to me, I have no problems with paying a couple of bucks (just don't make me pay before I've had a chance to check out what you have to offer), if it's not, annoying me with ads won't exactly put me in a spending mood either.
Or you fool yourself to rationalize bad behaviour. Not all people are selfish. Most are to varying degrees.