Things that aren't "can't focus" that are symptoms of ADHD:
- bad temper
- speaking before thinking (followed by immediate regret)
- often making spur of the moment decisions without thinking of long-term consequences
The overarching thing being that lots of people with ADHD do things _despite knowing on a rational level that it's not a good idea_, because that thought usually isn't loud enough to actually stop your actions (at least not fast enough anyways).
There's always a bit of "yeah everyone has that" when you talk about laziness and lack of focus, making it feel a bit like an unfalsifiable diagnosis. But there's a lot of people who most definitely don't have bad temper issues or go binge drinking all the time (Though this isn't everyone with ADHD either of course).
The symptoms you describe are impacted by the two elements I described (executive function issues and dopamine regulation).
People with AD(H)D have issues with regulation and executive function, which can lead to issues in how one controls themselves. This can lead to the issues of controlling oneself that you describe.
On top of that, dopamine (which is more accurately a "motivation hormone", which creates the desire to do things) is different in AD(H)D brains. Basically, people with AD(H)D will get a dopamine kick from certain types of behaviours, and not from others. This can result in the relative importance of tasks being very different from neuro-typical ordering. As a result, addictive behaviours can be more common (especially for things like video-games), or also the prevalence of hyper-focus that people with AD(H)D experience.
I agree with your last paragraph fully. The lack of understanding around the condition can lead many to make uninformed actions and opinions that can be harmful to those with AD(H)D, diagnosed or not. This can have negative impacts on patient mental health, and is the reason why people should be more aware of this oft misunderstood condition.