Light will always win?

[KaIadin he/him]

If good events have to equal bad events, does that not mean that if Rand died, the dark one would die/be incapacitated too? I've been thinking about this for a bit.

[Mulk he/him]

they aren't equal.  Ta'veren tugging generally causes chance to go crazy in roughly equal amounts, but there is nothing that says the amount of overall bad and good events are equal or have to be.  The purpose of their pulling is generally to put the Pattern back into line and while the Pattern itself isn't good or evil, part of the ongoing purpose knit into the Pattern is keeping the Dark One locked away.

Rand/Lews Therin has lived and died hundreds of times, probably in the world of WoT.  His death never has caused the death of the Dark One.  Nor has it freed him.  Nor has it incapacitated him.  He's just the one the Pattern chooses to fight the Dark One and lock him away.  Because the Dark One is continually trying to break free and trying to warp the Pattern to allow it, there is nothing that says the Light must always win.  Some day, the Dark One may win.  The Light may continue to win.  Or the Dark One might one day break free.

[Leyrann]

It is implied in A Memory of Light (this might be an addition by Brandon, but it might also not be, as much of the finale was written by RJ) that the Dark One can never win, as he cannot understand that there will always be people who will continue to fight, no matter how bad it looks, while he only wins once everyone submits to him.

I also do think that, if the battle on the Field of Merrilor had been lost, Demandred would still not have let the Dark One destroy the world. He cared about the world, and he wouldn't just let go of that.