through thousands of pages, and it’s just a sad, pathetic, uninspired, lazy ending.

I mean, it does literally warn you to stop reading when the characters other than Roland get their happy ending, so if you kept going that’s on you… /s

Also, it’s thematic to the story at hand. It also ends hopefully, as Roland has the horn he did not have the first time through, which is implied to be incredibly important to his quest going well. We see the cycle right before victory, when he gets everyone else their happy endings and redeems his sins enough to earn the horn and, on the next cycle, likely end his quest. Which can be read as very hopeful, but your take isn’t invalid or anything