I'll go.
Untreated mental health problems from day 1: probably either autism or dmdd. I struggled my whole life with outbursts, anger, and socializing. My parents are their own story. My mom definitely had some mental problems of her own and my dad is likely autistic too. Because of the way my dad was raised (he has shitty parents) I grew up in a household where showing emotions was shamed and self expression was embarrassing. Everything I did in my life I did to please my parents. When I had problems in my own life I hid them because I didn't want them to be embarrassed. Basically, I parented myself. It's caused me a lot of problems in the long run. My anger issues caused me a lot of problems but mostly instead of getting treatment my family just laughed about it at my expense. I still was unable to fit in with anyone at school. Then came junior high aka hell. I was overworking myself to exhaustion every day to impress my parents. I picked up sports and instruments just because I felt I'd have worth if I was good at something. When I wasn't perfect on anything id stab myself with pencils as punishment. I rarely has freetime. My sister began dealing with severe depression and anxiety. My family had no understanding of mental health so every day became a war between my older sister and my parents. Me and my brother would hide in our rooms as the screaming matches went on and on. Sometimes they debated taking her to a hospital, other times they tried to break down her door as she barricaded herself in her room. I just spent my time dissociating. We weren't aloud to make any noise in the house because it'd wake up my sister from her 24 hour sleeps.
Then came the bullying/abuse. I had these friends for a while who messed with my head. They were incredibly controlling. I had to eat lunch with them every day, and I wasn't allowed to have any other friends. If I failed to please them they'd spread rumours about me across the whole school. They also mocked me to my face, threw food at me, and stocked me online. The emotional manipulation was the worst, they made me feel like I was evil for not accepting what they did to me. They also shamed me for my interest and tired to make me their personal slave for them to vent to and receive adoration from. I was naive and possibly autistic so I put up with it, thinking that's what friendship is. Along with that my junior high was also littered with rapists and antisemites who would whisper threats to me (a Jew) in the halls. I was always scared I'd be killed one day.
Then came the codependent friendship. The first friend I made after escaping my previous friend group was a girl who was incredibly suicidal. She introduced me to self harm and I spent most of my freetime trying to talk her out of killing herself. We became co dependant and she would shut down when I had concerns in the friendship. My whole life began to revolve around keeping her alive. I'd try to predict her every emotion. She told me I was the only one she'd ever trust and that she'd off herself if I broke her trust. I took my job very seriously. While thsi was going on I was also dealing with my own severe depression and anxiety, along with undiagnosed bpd. I had a stint of suicide attempts and I had begun hating myself for my possible autism and inability to connect with people. This continued on for a while as I grew up. Highschool came and went with my mostly just thinking of ways to kill myself.
Then came the pandemic. Something weird happened. I started feeling agitated all the time. My memory got worse, my ability to focus tanked. I was having flashbacks to memories I had completely pushed away. I was having unbearable headaches that left me in bed in the dark all day. I think that being able to not do work of focus on surviving all the time was forcing my brain to actually process traumas. It lead to a full on mental breakdown. My personality changed, my emotions shallowed. Even my pain tolerance changed. I became delusional and convinced that I would die of dementia. Other times I thought I'd become a serial killer and so I tried to hide myself from the world. I began hallucinating as well and my thoughts grew more disorganized. I knew I'd never fully recover from what was happing, and I was right. This experience was the scariest in my life, and words will never do it justice. Eventually I was hospitalized where I witnessed even more traumatic things. Patients were mocked my the staff, and I was not immune from this. After discharge my life has been stagnant. I've attempted university with no success. I'm numb all the time, and I have no friends. My hallucinations and delusions are gone but the cognitive damage is permanent. I'm basically just stupid now. I only had one friendship after discharge and it was very one sided. He made me feel worthless all the time. Eventually I attempted suicide because of this.
It's not a bad story at all compared to others. I think it's just the developmental trauma that comes with untreated mental illness and family problems from day one. It's a bunch of little issues that build up to make me a disfunctional person.