The colonists you are given all have character traits and there is a social aspect of the game. Colonists can start relationships, start families, break up, start social fights and end up in infirmarry... Sometimes, family members of your colonists come to your colony as raiders. All these stories forming during gameplay is the real strength of the game for me.
For example, there was this one colonist woman in one of my playthroughs. She was the tough, soldier type. She started one or two relationships in the colony but ended them. Then she tried to go back to them. It started creating some complicated feelings among the colony so I sent her to scavenge a nearby abandoned base.
Before she can leave, a band of raiders popped in. One of the raiders was her teenage son! So I start getting so invested in saving the son and bringing him back to the colony. I'm not that skilled in combat or tactics so I save the game multiple times until a trap injures the boy so his mom can snatch him without fighting. She takes him into one of the intact rooms in the ruin and patches up his wound, shares her food. (She takes him prisoner and you can keep talking to prisoners and convert them into your colonists. )
Here is a scene where raiders running around outside, raiding. And a mother and son, hunkered down in a room, trying to reconnect.
While the boy is recovering in the impromptu prison room, she gets out and shoots the raiders one by one. Rest of the raiders leave the map after losing enough members.
Mother and son talk about family, son talks about some childhood memories. Eventually, he is no longer a prisoner but a newly recruited member of the colony. Woman comes back with her son. Son turns out to be a psychopath but that's ok. At the Rim, we love psychopaths, they do gruesome task of disposing raider corpses, for example, without getting emotional strain.
Mother stopped creating drama in the colony after son joined.
....
If you read people's stories in the steam comments (there are a lot of war crime simulator stories, too, be warned) you may get why it's so addictive.
For games specifically, I have to binge or I'll never go back to it and next time I wanna play, I have to start over. Books or TV shows etc. don't have the same problem as they are more passive consumption than a game.