Really beginner question: How is the trans community a threat to anyone?

Probably best to start with a trigger warning, as I will be covering molestation. Sadly, not the sort where moles are just doing their duties.

YouTube just served me this. (very much a trans-friendly link)

And I was basically left wondering who the hell feels threatened by others being themselves. I hope this will not come across as inappropriate from a nominally cishet male.

My background is hopefully not normal. At the age of 6, I was repeatedly involved in anal sex with a neighbour (his idea). Not to be outdone, a female cousin six years my elder babysitting me a year later introduced me to kinks that one should not know at 7 but would later inform my relationship choices in a less-than-ideal manner.

That would take another 23 years, but my first real relationship, in college, was with a woman whom I like to claim I lost my virginity to (so as to avoid having to bring any of this up) that I also ended up in discussions with about being a sperm donor for her and her wife years later.

After her, my year as a raver started. One learns very quickly not to assume a goddamn thing about anyone's sexuality or gender identity in that environment. It took two years in college to get to the point that I'd slept with more women than men, and just a few years ago, I started talking with a guy who I had to ask "are we flirting?" when our conversations felt more like what I was used to on intentional dates.

Hence "nominally."

So I have always been somewhat in orbit of the queer community without ever considering myself part of it. Indeed, a big reason I chose Beehaw was because inclusivity is just the sort of thing one should engage in.

But this video was a maddening experience (I mean, I totally agree with the presenter), given that I don't see who's threatened by the existence of the trans community. Unless you're pinning me down and forcing me to do things I don't want to do, what you do in your life is not my concern.

I again apologise for what is likely a very basic question, but I just don't get this. There are so many things to be concerned about in the world, and my god, I thought we'd gotten past petty shit like othering people. How my second wife was proudly bi and somewhat racist (first wife, same deal, minus the racism) was a confusing juxtaposition, but I was in a bit too deep by the time that became apparent.

After that divorce, I ended up with a coworker I didn't even realise was a lesbian (she'd say I turned her bi), so straight is simply not normal to me. How is this a standard assumption, and how the existence of trans people are an existential threat is baffling, unless we take the view that straight people have more kids, which is what capitalism needs to forever feed the growth beast.

Is it as simple at that? I'm going through some stuff currently that makes me ill-equipped to dive down the research rabbit hole, so I'm reaching out here in the hope of understanding without spending several hours getting angry.