Hey, I know you weren't trying to cause offense but i'm going to try to explain it a bit for you. I used to think it was crazy too and couldn't understand how people couldn't just not do it, but then I had a bit of experience with it myself.
This is mostly based on my experience either personally or from what i've been told so won't be the same for everyone.
I'm not trying to cause you offense either so if something sound it please don't take it personally- it's just poor choice of words.
You will probably know it's bad and not helpful (op does which is why they are asking for help). And although you are part right in that being an important step it's the easiest and there's a lot of struggle after that. People eat burgers and chocolate becaue it makes them feel better despite knowing it's bad for them and sometimes it's like that- immediate gratification despite long term negative effects. Sometimes it's more complicated though- there's a level of compulsion to it.
For me I found I just couldn't get it off my mind and eventually it got too much. I'd held off for months pushing the temptation away and taking the logical option, but it got too much and I gave in. It was tiny and there wasn't much negative so I gave in more easily after that. I'd know I was being stupid while I was doing it and sometimes that made it even worse. Emotions just turned into actions without me really knowing.
I was lucky and when my mental health improved those feelings did too, but untill thenn i was living in some crazy world where I had no control over my actions or thoughts. I was trapped in my own body. In a time like that where the world doesn't make sense logic starts to become less and less meaningful. I had tried relaxing and music and distration and all tose othe better options but none of them took the thoughts away. Hurting myself was the only thing that dragged me out of my own head enough for some slight release. The self loathing that followed was almost better than the temptation actually.
Even after I sought help there was still a long road to recovery. You need to change your whole way of thinking and it's hard. To be honest, I still turn to it sometimes when i'm at my worst. At those times where my support seems to be failing, but after getting help I now have the stregth in myself to fight it. That's something I didn't have before.
Anyway the basic point is that when you're in a depressed state logic doesn't always work. It's really difficult to comprehend until you're experienced it. Even for me, looking back, it's kinda like trying to explain a colour that doesn't exist. It's such a different way for thinking and feeling that it's kinda like being in another reality. Now that i'm out of it, I can't really understand how i felt so I can understand how it's so difficult for other people who have never experienced it.
I hope that wasn't too long and that it at least kinda answered your curiosity.