You're right, I too have a high level of curiosity and interest in phenethylamines even if I'm not taking or making them.

My interest centers around two main reasons, the first is that such simple molecules can have such a dramatic effect on the brain and that relatively few changes to the basic amphetamine molecule can elicit such large changes in one's perception (i.e.: from one molecule to the next).

The second is that I'm always been surprised about how little of these chemicals are needed to have an effect - we never talk in grams, which itself is a small enough unit, but rather always in milligrams.

It's not only drugs but also poisons where milligrams can kill within minutes or even seconds - we all know how deadly chemicals with the structure x-CN are and how little of them is needed. I see an analogy between these chemicals and electronics. They act somewhat like high gain amplifiers with control circuits attached - that is they have gain as well as great specificity of action.

I don't take a huge interest in how individual phenethylamines are made but rather the fact that there are so many of them and that there are so many ways of synthesizing each one. As soon as some precursor becomes difficult to get then some ingenious chemist finds a substitute together with a new method of synthesis.

I'd say I'm more curious about chemists who are even more ingenious than those mentioned -
those who break new ground in chemistry. Especially so when it comes to the synthesis of iconicially difficult molecules such as strychnine. This notorious and highly toxic poison (I know, as an evil bastard poisoned my dog with it when I was a kid and I watched horrified as he died in agony) - is also notoriously difficult to synthesize and has always been a challenge for chemists. It's the go-to molecule to synthesize if one wants a challenge, its synthesis challenged the greatest of chemists until the legendary Robert Woodward and his team managed to do so in 1954: https://en.m.wikipedia.org/wiki/Strychnine_total_synthesis. I'd reckon, even today, if one came up with a new synthesis for it then one would be recognized to be at the very top of the profession.

You say reading about phenethylamines is one of your favorite internet rabbit holes. Whilst it's mine and obviously that of many others too, I'm somewhat paranoid at spending too much time doing so for fear of attracting too much attention. I had this feeling the last time phenethylamines came up on HN some five months ago, especially so after I followed a poster's link to Uncle Fester's (aka Steven Preisler) Secrets of Methamphetamine Manufacture which turned out to be on Wikileaks (I later learned it's also on the Internet Archive which is perhaps somewhat more innocuous (but likely not given the book's notorious content)).

BTW, I think that Preisler's publication of this document was irresponsible for all concerned -
not for publication of the chemistry per se but rather the huge amounts of volatile chemicals he recommends without giving all the necessary warnings. Some novice could easily kill himself and others around him if Preisler's directions were followed (the quantities he suggested were more in keeping with those of a registered pharmaceutical lab than a backyard chemist). You can't blame responsible people for being concerned with such publications and I said so in a follow-up post at the time.