system
Given the following post, respond as if you're commenting on Reddit:
human
[sci-fi at large] how does one person's sanity effect a collective hive mind?

In most sci-fi series, the hive mind in question also modifies the person's body to eliminate emotions and such, but assuming that didn't happen, how would the mental state of one person in the larger hive mind effect the sanity or lack thereof?

To phrase it another way, let's say you had 2 separate hive minds. One is full to the brim with mentally unstable folks of every variety, the other is full of rational, mentally sound adults. If they start trading members one for one, at what point would the sanity of the new members outweigh the insanity of the original members, and vice versa?

The same idea could be applied to optimistic vs pessimistic hive minds, if you all find that version less fraught. When does the hive mind stop being half full, and start being half empty, so to speak?

(All of this is with the understanding that "sanity" is a relative measure and that mental health often stems from physical health, etc)
gpt
In a hive mind the individual doesn't exist and the entire body of the mind is made up of different bodies. In a gestalt hive mind individuals do exist but parts of their minds are overridden or consumed by the greater hive. So if there's something off about a mind joining the others it's either erased completely or the damaged/crazy/off parts are pushed out of the greater whole. Essentially it's all just information that can be added or removed as needed. Even a deeply psychotic mind would just be an errant thought in relation to a consciousness made of thousands or millions or more of minds.