Okay, but I'm going to try and explain it some more, because neither right nor wrong is winning. As Spike said in Fool for Love said!
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SPIKE: "Well, yeah. I suppose you're telling me you don't? (laughs) How many of my kind reckon you've done?"
BUFFY: "Not enough."
Spike nods.
SPIKE: "And we just keep coming. But you can kill a hundred, a thousand, a thousand thousand and the enemies of Hell besides and all we need is for one of us- just one- sooner or later to have the thing we're all hoping for."
BUFFY: "And that would be what?"
Spike leans in close and whispers in her ear.
SPIKE: "One... good... day."
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The forces of good never win! And neither will the forces of good, they'll always continue fighting. I'll ilustrate this with an even better example, which may even be the best diaglogue on B/A ever! Angel and Holland Manners from 2.15 "Reprise".
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Holland is standing in the open doors of the elevator slowly clapping his hands. Angel walks slowly closer.
Holland: "Congratulations. Great victory."
Angel: "You're..."
Holland: "Holland Manners."
Angel: "...not alive."
Holland: "Oh, no. I'm quite dead. Unfortunately my contract with Wolfram and Hart extends well beyond that."
Gives Angel a big smile, then motions his head.
"Hop on in. You certainly earned it."
Angel slowly steps in, looking at Holland, who laughs.
Holland: "No. Not a ghost here. No, it's just me. Dead me."
(Pulls the collar of his shirt aside to show Angel Darla's bite marks, then reaches for the elevator buttons)
"See? - Home office, wasn't it? I should mention the trip is one way."
Angel stands in the elevator looking out, not saying anything.
We see a homeless person pushing a loaded down shopping cart across the plaza in front of the elevator.
Holland: "Well, if there are no objections, I suggest we get going. It is rather a long ride."
Holland pushes the 'down' button. The doors close and we see the elevator descending down the elevator shaft.
Angel and Holland are standing side by side in the elevator as the lights from the floors it is passing flash by and typically annoying elevator music plays in the background.
Holland: "Well, this is exciting, isn't it? (Smiles) Going straight to the source. - So, what's the big plan, Angel? Destroy the Senior Partners, smash Wolfram and Hart once and for all?"
Angel: "Something like that."
Holland: "Hm-mm, now tell me just what do you think that would accomplish? In the end, I mean."
Angel: "It'll be - the end."
Holland: "Well, the end of you, certainly. But I meant in the larger sense."
Angel: "In the larger sense I really don't give a crap."
Holland: "Now I don't think that's true. - Be honest. - You got the tiniest bit of 'give a crap' left. Otherwise you wouldn't be going on this Kamikaze mission. Now let me see, there was something - in a sacred prophecy, some oblique reference to you. Something you're supposed to prevent. Now what was that?"
Angel: "The apocalypse."
Holland: "Yes, the apocalypse, of course. - Another one of those. Well, it's true. We do have one scheduled. And I imagine if you were to prevent it you would save a great many people. Well, you should do that then. Absolutely. I wasn't thinking. - Of course all those people you save from that apocalypse would then have the next one to look forward to, but, hey, it's always something, isn't it?"
The elevator shaft and cable dissolve as the elevator continues to plummet into a hellish red glow.
Angel: "You're not gonna win."
Holland: "Well - *no*. Of course we aren't. We have no intention of doing anything so prosaic as 'winning'."
Holland laughs and for the first time Angel turns his head to glance in Holland's general direction.
Angel: "Then why?"
Holland: "Hmm? I'm sorry? Why what?"
Angel: "Why fight?"
Holland: "That's really the question you should be asking yourself, isn't it? See, for us, there is no fight. Which is why winning doesn't enter into it. We - go on - no matter what. Our firm has always been here. In one form or another. The Inquisition. The Khmer Rouge. We were there when the very first cave man clubbed his neighbor. See, we're in the hearts and minds of every single living being. And *that* - friend - is what's making things so difficult for you. - See, the world doesn't work in spite of evil, Angel. - It works with us. - It works because of us."
And with that the elevator comes to a screeching halt. The doors open and Angel looks out to see a homeless person pushing a loaded shopping cart across the plaza in front of the Wolfram and Hart Office building in LA.
Holland: "Welcome to the home office."
Angel: "This isn't..."
Holland: "Well, you know it is. - You know *that* better than anyone. Things you've seen. Things you've, well - done. You see, if there wasn't evil in every single one of them out there
(Angel watches as some people in the plaza start yelling at each other)
"why, they wouldn't be people. - They'd all be angels."
The glove drops from Angel's right to land on the floor of the elevator and Angel slowly shuffles out of it. Holland calling after him as the doors close
Holland: "Have a nice day."
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Okay, I don't think I really need to add anything, the First Evil also said it in "Amends" it was in everything, the world works because of it, since without evil their would be no good and in fact their would be nothig at all.