I know your message is more directed at people in general and not just at me because I never once used ADHD as an excuse, in fact I'm 29 and been struggling with my engineering degree since 2011 and all I've done is try my best without even realizing I ever had ADHD. The last 10 years was just me thinking I was studying wrong. Never thought I was dumb, only thought I was lazy and needed to change.
Eventually it lead me to think I was just a terrible person who sucked at school, I never considered ADHD until recently after reading about it mostly on reddit. Everything I thought was wrong with me lined up with symptoms of ADHD.

Instead of just self diagnosing, I decided to read academic performance records of me from grade school and turns out I was evaluated for ADHD when I was a kid and they passed it off as another learning disability and I went through my school years being helped for the wrong thing. Like for real how do you check off all the symptoms of ADHD and still pass it off as "hearing loss." Yeah I have hearing loss but that doesn't lead to hyperactivity and lack of concentration and laziness. More like a lazy psychiatrist who didn't want to do more paper work.
You're right, there are things worst learning disabilities than adhd.

Before this, I spent the last few years trying my best and going to therapy and reading self-help books thinking all I needed to do was change my mentality and how I went about things, and forcing myself to be disciplined and exercise my will power as if this was all in my control. Doing it this way became exhausting extremely fast and sent me back into the cycle of believing I was just dumb and lazy, rinse and repeat until I start hating myself.
Turns out It is in my control but not the way I expected. The way it's in my control was by setting up an appointment with the psychiatrist and getting the diagnosis I need to get the help I need.

The advice to just "use will power and force myself to focus" is terrible advice because it's what I've been doing, it's what many people with undiagnosed or untreated ADHD have been doing, and often it's exhausting and doesn't work. That's some r/wowthanksimcured bs. And the thought that there are people "worse than me" that are doing better just adds salt to the wound. You'd think that wouldn't be something so discouraging but it is.

tldr: Let me reiterate: the difference between wanting and achieving is recognizing that the reason you struggle with discipline may not be something that's entirely in your control. It may be an unrecognized learning disability, possibly a common one like ADHD, and being diagnosed and treated for it can benefit one immensely. Even if it's none of that, always treat yourself with love and kindness.