When hydrogen is burning, water is formed.

It's the wavelength of the flame that messes us up. It's very blue, with large parts of the energy placed in the invisible UV-range. (It's also strong in the IR range due to water.)

A safety advantage is that the hydrogen disperses quickly and is lighter than air.

A safety shortfall is that a flame burns invisible if there is any leak. You need either a thermal camera or a lost limb to find it.

How are they going to deal with that risk among a non-professional user base?

Yes, that is true! Secondly, it's hard to control for statistically since patients with gender dysphoria are usually investigated much deeper.

Yes, I consider such frivolous diagnosing to be damaging. I've witnessed it myself (no further comment).

Still, identifying and helping the individual challenges of the patient is a necessity considering the amount of discrimination in today's society. You need to be a very well balanced and strong individual to thrive in that situation, if not barely survive. At least in my country, this is how it's supposed to happen.

Hopefully, when society matures less intervention will be necessary.

Human emotion is seldom logical, even if one can find an evolutionary reason for their existence. They are only rules of thumb than on an average have increased fitness in a world much different from our own. What is well known is that most of us are born with a gender identity that long-term is emotionally very costly for us to go against. (See the result of tragic surgical experiments on intersex children.)

Our brain is optimized to find patterns. In a society were only women wear skirts, an individual with a completely masculine identity will not want to wear one. Of course a skirt has nothing innate feminine about it, but in that culture it does.

In a hypothetical society were the only difference between men and women was our bodies, gender dysphoria would still exist. But it would probably be more focused on physical differences.

My pet theory is that gender identity is primed by primitive signals, e.g. pheromones (e.g. https://academic.oup.com/cercor/article/18/8/1900/285954?login=false for corroborating experimental findings). During our childhood our neocortex couples that to the patterns in the world we find. That pattern can change depending on society and circumstances.

There are probably three phenomenons at once, all usually championed by different people with different political agendas:

1. Health professionals that try to protect the patient from regret and/or mistreatment, thereby over diagnosing any mental problems that is remotely possible. Most persons have some weaknesses in their personality, but at a sub-clinical level.
2. Gender dysphoria tends to make your life hard. Said weaknesses might then develop further or suddenly become a problem.
3. Gender dysphoria is a deviation from the neurological norm. In some cases there might be an underlying factor that caused both a deviating gender identity and some other neurological condition.

But I strongly find it not probable that a mental disorder causes gender dysphoria. In the same way that it doesn't cause homosexuality. Most of us have a gender identity disposition that we're born with that blooms in our early childhood. That is completely normal as long at it agrees with your physical sex. In a well developed humane society, a deviating gender identity should be constructively taken care of. (e.g. gender transition and acceptance from the rest of society.)

The science is not complete on the etiology, but we know there is a genetic link to the genes linked to the degree of feminization and masculinization (e.g. https://academic.oup.com/jcem/article/104/2/390/5104458?login=false). If you do a quick google scholar search, you will see that there is a lot of really good arguments for that it's biologically linked. Genetic, hormonal and environmental during the fetal stage of development (when your mother was pregnant.) In other words, with today's science our best conjecture is that gender dysphoria is caused by a brain born with a gender identity disposition deviating from birth sex.

Personally, I wouldn't be surprised if the truth includes a little bit of all of these three explanations. We will probably find that there are several complex biological paths to gender dysphoria, e.g. combinations of hormones during the fetal stage, genetics, teratogens (toxic chemicals) etc.