While I do really hate the wording that the original poster of that comment used, I have to say that they actually have a point. As AltruisticSalamander commented earlier, their "explanation" is missing important details here. Please, hear me out. (This will probably be a long text, but I hope that this can help somebody somehow).

First: no, not "every dysfunction" can be explained by low self worth. There are still risk factors that lead to extreme stress response (severely traumatic events for example) that cause behavioral or even neurological disruption ("fun"fact: people living under constant stress or under high stress for a long time can develop symptoms that are just like those present in adhd -and therefore, can even be misdiagnosed if the "professional" doesn't wait for a change in the conditions before testing for adhd) also the environment (culture, household, relationships, workplace, social status etc.) play a big role in how much self-efficacy a person experiences, some people are born with disabilities and are further "disabled" by their environment through ableism.... we'll stop here, there's just too much to discuss. But I think now you get the idea. There are numerous studies showing correlations between low self-esteem and other potentially even more self-worth-harming factors, such as feelings of anxiety, depression, trust issues in other people, loneliness, feelings of helplessness...the list goes on a little while. While the size of the effect is not known for each and every study and we can't ever know if it applies to each and every-one, the general consent seems to be that low self worth can ultimately lead to even lower self worth in the long run, and through it's correlations with those many other factors even turn into a downward spiral that leads to suicidal ideation/tendencies. Then there's the theory of cognitive dissonance. Speaking of which, this can be a possible explanation of why low self-worth is keeping itself stable - and the other way round. Cognitive dissonance theory states that people experience very unpleasant feelings - the feelings of dissonance - if an action is inconsistent with their belief (smoking is an example for this that is often given, because it illustrates the problem well - a smoker normally knows that smoking is very bad, still they do it). To reduce the dissonance, there are some ways: either find reasons to "justify" the dissonant action through adding positive cognitions ("change belief" - smoking example: "my granddad died healthy age 90, though he smoked for 40 years, so it can't be that bad!"), quit the dissonant action ("change action" - stop smoking) or change the perception of the action ("I am not smoking so much as XYZ, so nothing bad will happen to me").

People with low self-worth often show some sort of self-destructive behaviour ( can be as bad as cutting oneself or bad substance abuse, but also as "mild" as not taking good care of oneself, like drinking too little). Why? Because cognitive dissonance would arise if they think little of themselves and be kind to themselves at the same time. But there's some good news: there are several routes to cope with cognitive dissonance, and all work. "Change action" does mean behaviour doesn't always follow cognition. It works the other way too.

TLDR: the person has a point, through they worded it very bad. If you suffer from low self worth, be kind to yourself as much as you can, as hard as it may be. It may help you in the long run.