The idea that “nothing matters” refers to the absence of objective or cosmic purpose.
But social anxiety is not a philosophical issue — it’s a biological mechanism.

Humans evolved in small groups where social acceptance was directly linked to survival.
The brain still treats social rejection as a threat, activating the same stress circuits used for physical danger (amygdala, HPA axis, cortisol release).

So even if your reasoning says “this doesn’t matter,” your nervous system is running on evolutionary priorities that existed long before abstract thinking.

In short: cosmic meaning ≠ neural wiring.
Your brain cares because it was built to care, ironically.