system
Given the following post, respond as if you're commenting on Reddit:
human
[D&D] What's life like in a Duergar society?

I know this varies from edition to edition and world to world but I'm looking for the broad strokes in varying situations. 

What's a Duergar family like? Do they even believe in a nuclear family or some kind of cohesive social unit? 

What's a Duergar business like? 

What's a career (life?) like in their military? 

Religious institutes? 

From what I've read, Duergar appear like a very austere and pessimistic race that mostly values material labor. They also have a deep mistrust of others within and outside their society. While not necessarily purely greedy, Duergar focus on what furthers their own gains with no regard to concepts like altruism or intrinsic value. Despite all of this, I wonder what really motivates a Duegar society? They keep their own faiths, run business, and have a surprisingly functional society with sophisticated cities and institutes. There's history and bad blood between races, but that doesn't really explain what Duergar do with money, free time, or how they see their goals as individuals?

I know the experimentation done by the Illithid plays a large part in all this but it can't all be biology.
gpt
> What's a Duergar family like? / What's a Duergar business like? 

I would guess that duergar view mating and child rearing as a loveless business affair.  A prospective suitor wants a man or woman for the synergy they provide in some industry or another.  They are judged on their ability to fulfill their end of a contract and bring wealth and prosperity to the deal.

Children may actually be part of the initial dickering as well.  For example, a young duergar wishes to secure a coveted exclusive contract as a wheelwright with an Underdark caravan.  He proposes a partnership with a woman whereby she shapes the felloes while he forges the strakes.  To grow the business they plan to add children to work the bellows, fetch the water, grow/harvest the fungus-wood, lathe the spokes, etc.

When the kids are old enough they each evaluate their own prospective profits and either strike out on their own or continue a working partnership with their family.  Clan loyalty doesn't factor into it.

> What's a career (life?) like in their military? 

Military life is somewhat like becoming a slave.  You indenture yourself to an outfit with the hopes that it will lead to profits in the form of wealth and power later in life.  It's also a necessity to learn how to fight in the heartless world of the duergar.  No one will come to your aid if you need it, so becoming strong yourself is the only way to survive in the long run.

> Religious institutes? 

According to *Underdark*, duergar worship Laduguer, the dwarven deity of toil.  Doing their work is their worship.  They don't assemble for ceremonies and pageantry.  They may produce works of art to dedicate to their god if they believe it will somehow profit them later on.

> explain what Duergar do with money, free time, or how they see their goals

Their endgame is the actual industry itself.  They don't save money for luxuries - everything rolls back into the business.  Better equipment, more slaves, bribes for contracts, etc.  They work so they can work.