> If you're in a world of mass opinion and mania where ideas spread virally it ceases to be an indicator.

Not really. It continues to be an indicator, just a less reliable one. As I said, it's one heuristic. It increases your probability of being right more than it decreases it, but it isn't an absolute rule.

Fundamentally, science itself relies on this heuristic to some extent. The idea that an experiment be reproducible is essentially the idea that the majority of testers should agree on observed reality. You just have to be careful not to conflate opinion with observed fact, or to treat it as more than a heuristic evaluator.

> Happiness decoupled from truth is nihilism.

Not at all.

You do not need to be correct to be happy, and there is no correlation at all between your ability to correctly understand the world and your capacity (or worthiness) to experience joy or to help others experience it. You are allowed to be wrong and happy, or apathetic and happy, or ignorant and happy, or even nihilistic and happy.

> If that's the goal start doing heroin at ten in the morning and retreat into the VR world of your choice.

There's more than one type of happiness. The kind you describe is hedonic. The other type is referred to as Eudamonic, and it comes from connection, service, and a sense of purpose.

You'll never get to experience the second type if other people don't want to be around you because you've decided that your own narrow perspective is the One True Perspective (TM).

Don't get me wrong, I reject post-modernity and the horrifying idea that there is no objective truth. I just also reject the idea that any of us are valid arbiters of that truth, or that we must know the truth before being allowed to experience happiness.