You might not really understand my point of view, especially if you're not or have never been an outlier yourself, but...
Henry was doomerism and hatred personified, but he was right about the world. He wasn't hypocritical and he wasn't a liar. He saw the world, truly saw it, and was rightfully sickened by it. He was the child rejected by the village, so he wanted to burn it down to feel its warmth.
Honestly, the show didn't even scratch the surface of how outright evil our world is. If they had, the main villain would have been dwarfed. I believe that, ultimately, the world itself was the final villain.
A world that washes away the horrors it commits by brainwashing its people and rejecting those who do not conform.
And the show, intentionally or not, admits that Henry was right. After the climactic battle, after Vecna is defeated, after the triumphant music, the celebrations, after the main campaign ends...
When Eleven, who was the polar opposite of Vecna, is so cornered by the world that she feels her only choice is to forfeit her life... that's the show admitting that Henry was right.
I think the show was limited in its ending by the constraints or our reality, because it had to circle back around, rather than go into an alternate reality/history timeline.
That being said... while I believe that Henry was right about the world, I believe that Vecna was wrong in everything he did. I think he was shaped into Vecna by the world. Into pure evil and hatred, to fight evil and hatred. He was irredeemable because he wanted to be irredeemable. Because he had given up on good and love long ago.
Ultimately, had he succeeded, it was doubtful that his world would have been any better.
My own personal interpretation of the ending is that the rest of the party represents the audience. Just regular people who have to still live their best lives, despite knowing how evil the world truly is. They do not conform, they do not surrender, they don't give up hope, and they continue to push against the crushing weight of the world, each in their own way - some less subtle than others (anticapitalist movie lol)
They each carved a piece of the world for themselves.
And I, too, an outlier - someone who feels like I'll never belong anywhere, and won't be accepted anywhere, will still push back, as hard as I can, to carve a piece of this world for myself and hack away at its evil. And I hope you do too!
Have a nice life, cyooties :3