An experience which has made you feel lesser than you are.
My mum has believed she is stupid and worthless and to avoid people who are capable as they will see her as she is and put her down because of this. This has come through the nature of the education system in the 60s and 70s and then from an abusive relationship.
My sister had to drop out of her a levels in part because of how the school treated her being stalked by a fellow pupil.
My primary school assumed because I was quiet and reserved I was dim. Thankfully I had supportive parents who gave me self worth but many without that support would believe the teachers when they put in reports that you "had fluked good results"
I experienced discrimination in my undergraduate degree and my PhD. I do have a mental health condition but with support and treatment I can manage. My undergraduate tutor told me "depression was a girl problem and he didn't deal with girl problems" and my post graduate supervisor engineered an almost impossible situation to come back from.
Some many people that come from difficult situations will say things along the lines of "I had the food fortune of finding a course that fitted alongside my 3 jobs" or "I had a mentor that inspired me". Those with bad luck look for a course that will help them do something but that course only runs on a Tuesday at 8am and it was impossible to get there in time or found a course but it cost £3000 to do it and I was already in a negative budget.
At one of my previous jobs we had a series of talks from people further along their career talking to those of us that were just starting. Once spoke about how she was able to restart her career after her husband died because of the kindness of her daughters teacher. Her daughter has just started school and she had been able to negotiate finishing at 3 to pick her daughter up at 3.15 and completely the rest of her hours once her daughter was in bed. In the meantime the school changed it's hours so that it finished at 3 (in an era before after school clubs). She broke down on the teacher and said she didn't know how she was going to keep working. The teacher said don't worry, I will keep hold of her until she got there whether that was 3.05 or 3.15. This was good fortune that allowed her to restart her career. It doesn't take much of a stretch for there to be a different universe whether that happened and there was no one else to get her and she had to seek out a different job or give up work entirely because it didn't fit with family life.
If you can look back on how you got from where you started to where you are now and say yes I worked hard and it paid out but I was fortunate that more often than not a solution could be found and that allowed me to improve my situation it doesn't take much of a leap to think there might another person where instead of a solution at each turn further problems arose?
My dad worked in china for several years when I was a child. He spoke to one of the female interpreters, she was one of the best but in a more junior position. She told him that she had been unable to afford to get the qualification that would allow her to move up to higher positions. It was a lot of money for her but affordable to someone on western earnings. There were three people from my dad's company working there and together they paid for her to get that qualification. She quickly moved to a new role earning far more than she was before. She had the good fortune of meeting people who were able to support her getting the qualification she needed. How many other women that didn't meet people like my dad and his colleagues who never moved on from starting position ?