If a being is in a situation where it’s unable to escape or respond to things done to it, over time it’ll often stop attempting to do so, even when the situation changes.

An example being an elephant not trying to rip out a chain from a wood post because it didn’t work when it was a baby. It can easily escape now, but it still thinks it’s trapped.

It’s a similar thing with humans sometimes, it’s hard to thrive and prosper when all your brain can think about is how to prevent past trauma from reoccurring, that they don’t deserve a better life, or even that self improvement isn’t possible.