I agree. I wouldn't recommend anyone to self-diagonse themselves either. If somebody was to really doubt their handedness, he/she should have their handedness tested by a professional. However, sometimes, it can be very obvious to "recognize" a converted left-hander. For example, if somebody does everything with their left hand, except for writing.
Many of the problems I listed above may also have a different background and cannot solely be deduced by a converted handedness.
1. I've yet to see you cite a peer-reviewed study that has appeared in a medical journal of any significance to the effect of either statement.
2. Your "list of consequences" are far too common and could easily be attributed to pretty much anything from cancer to "bad chi."
3. Despite the previous point, I still experience none of your "primary" symptoms with any regularity and only one of your "secondary" symptoms, which are so common that I'd be surprised if someone didn't have at least one. That particular "symptom" could be attributed to, again, pretty much anything (including my personality).
For the record, my handedness varies based on the task I'm doing, and I have no degradation of skill nor cognitive function regardless of which side I happen to be favoring. Some tasks I do (like playing the violin or playing video games with keyboard and mouse) require me to do different things with both hands, which I'm perfectly capable of doing without confusing left and right or biting my nails.
This whole thing reminds me of scam-artists I've heard of who reel you in by listing off a bunch of common symptoms that pretty much anyone has at least one or two of, then proposing that they can cure it with some sort of cure-all remedy. Only in this case, instead of getting rich off of it, I can't even tell what you're getting. Validation? Acceptance? I have no clue. Maybe you're genuinely convinced this is true because you've read a lot about it. There's also a lot of literature out there denying climate change; that doesn't mean it's not happening.
I have no doubt that some people could experience severe problems if they (a) do have a dominant side and (b) are forced to use the other, but I do doubt that (a) no one has a dominant side and (b) everyone who uses their non-dominant side will have problems (especially ones as common as you say).
I don't really understand what is so hard to "believe". There's nothing to "believe" in or not about this topic. It's not like I simply claimed things that haven't been approved. All of what I've said in my opening post has been approved by professionals. There's a variety of professional literature regarding the topic in which you will find all the things I've stated.
Professionals agree that there's no "true" ambidextrousness. This is because, there are two hemispheres of which one is always dominant. As one hemisphere is always dominant, a person's handedness is determined as well. A "true" ambidextrous person would e.g. reach for a glass with both hands simultaneously. Normally, this doesn't happen.
I know a left-hander counselor who has been testing people's handedness for over 10 years and she really has tested plenty of people. Many of them claimed to be ambidextrous but during the test, she has always been able to determine every person's dominant side. She says that she has never encountered a "true" abidextrous person. Most of the people who claimed to be ambidextrous were converted lefties.
I used to think that I was ambidextrous as well because I could do everything with both hands. When I first heard of the term "converted left-handers" and heard that ambidextrousness doesn't exist, I felt very relieved. Over time, I started to realize that I must have converted myself when I was a child. Some memories came back which confirmed my hunch.
Really, being a converted lefty is hard. When you first realize that you're converted, you feel very happy to have found out the truth. When I started writing with my left hand again, I felt so overwhelmed. I felt like myself. When you're a lefty and write with your right hand, it feels like there are blockades in your head. I know many people won't understand this but handedness is a big part of one's identity. And if this identiy is somehow "broken", you don't quite feel like yourself and don't feel comfortable. I always knew that something wasn't "right" but couldn't tell what it was.
The main reason I started this thread was because I wanted to help people. I figured there must be a lot of people like me who know that something isn't right but can't tell what it is. It's important to raise awareness in order to help people. And that's what I'm doing.
I understand what you say about the problems being very common in general and may not have something to do with a converted handedness. This is correct.
However, problems with writing are very often associated with other things and many people overlook the possibility of a converted handedness being the reason for this problem. I think it's important to raise awareness that a converted handedness can be a reason for those problems. Like I said in my opening post, many adults see a therapist but can't be helped as therapists don't know the problem of a converted handedness. If it was common knowledge what a converted handedness can cause, I believe, many people could get better treatment.
I'm not implying that every converted person has to suffer from one or some of the problems mentioned above. But especially problems with writing and confusion of right and left have been extremely common in converted left-handers.
The reason why depression and burnout are often a cause of converted handedness is easy to explain: Because of always using the wrong hand for a procedure as complex as writing, people get tired, exhausted very easily. Like I said above, writing with the wrong hand costs 30% more energy than it normally would.
Again, I know that all of these consequence I listed above can have a different cause than a converted handedness. But it's important to make people realize that a converted handedness can cause these symptoms as this is almost completely unknown in society.
Well, if you are convinced that you're ambidextrous, then I won't tell you differently. I can only tell you my experiences and knowledge and can't speak for everyone else. However, professionals do agree that ambidextrousness normally doesn't occur in people.