I just don't get why some people voluntarily put themselves at the bottom of the list when it comes to what they need, while putting other people's needs on a pedestal.
I grew up being trained to do exactly this. By adulthood it was well ingrained and still being expected of me. I didn't even know I was doing it, it was subconscious. People don't know what they don't know.
Every time I'd attempt to set boundaries of any kind (not something I knew how to do properly, having grown up not being allowed to have any), the people who wanted to use me would get angry or be manipulative and, of course, believing their needs were more important than mine and that saying no, however politely, was rude, I'd set about appeasing them. Alongside sometimes trying to persuade whoever-it-was to allow me to do whatever thing I didn't actually need permission to do, if only I'd known it.
Even if decent friends said they wouldn't put up with something, I used to think: my situation is different because you're not me. So deeply entrenched was the dysfunctional ways of thinking. So until a therapist pointed out it was happening and told me I didn't need to tolerate rude people (which is what getting angry/pushy/manipulative/passive aggressive at someone having boundaries is, however polite the tone of voice it's done in), until I was told that I was justified in literally walking away from anyone behaving like that, both in the moment and long term getting them out of my life - I had no idea.
Emotional abuse is like the brainwashing of cults. Sometimes the cult members are free to leave and they have access to the outside world so could do so, but they stay because they believe staying is the right thing to do or because they've "voluntarily" given all their money to the leader, even if they're putting up with abuse of some kind (not that they may always recognise it as such).
Nobody was openly telling me I couldn't do xyz, nobody was beating me up, nobody was going in my purse and stealing my cash - but there were consequences for making the "wrong" choices, all the same. The "right" choices being the ones others wanted me to make, the choices that benefitted them and sometimes harmed me. Those consequences made making the "wrong" choice not worth it. I wasn't in a cult, but I was being controlled by those around me. Yet if you'd asked me, I'd have told you my choices were my own, that I had free will and control over my own life, because I believed it to be the case. I was wrong.
If you grew up being allowed personal autonomy and to set age-appropriate boundaries, then to you it's common sense to look out for your needs. I wasn't allowed to have needs, never mind wants too. It blew my mind to discover that not only was I allowed to, I was supposed to - and what's more I don't need anyone's permission, don't have to justify my needs to anyone else. I was 30 before I learned what boundaries were and that I was supposed to have some, then started working on it. Prior to that I was a people pleasing doormat under the illusion that I had control of my own life, but really just a puppet being controlled by my partner, most of my family of birth and about 50% of my "friends" - if only I'd realised it. It took me years to be able to put boundaries in place with people effectively and stick to them.
There's a lot of people like me out there. I didn't grow up in a horror-film family, just an ordinary one that looked like any other, on the surface. We looked happy. My parents had normal, ordinary friends. Other parents let their children come for playdates at our house and had me over to theirs. I was well behaved at school and at home. I had friends. You'd have had to become part of our family, living with us for a period of time, to realise there was anything wrong with it.