I find the hypothesis that the "original" is *just* equal to a past "me" therefore irrelevant, that my current "brain state" is in all purposes exactly as if it was just teleported from my previous "brain state" just a plank second ago (or something), a very intellectually interesting one.
To call the skepticism of this idea an "illusion" is mind boggling to me. As far as I am concerned, even if such technology could be possible, there would be no way to reliably test that idea. It's an unfalsifiable idea. If it is true, then the teleported person will act as if it was true, if it is false, the teleported person will act as if it was true, with the difference being, it's not really you anymore (you died, sorry about that).
It's the untestability of this idea that gives rise to the horror of it all. Star Trek might well be filled with creatures that constantly kill themselves and are being eternally substituted by exact clones without even noticing it, without anyone ever even be aware of it or even know the possibility of it (except the brightest paranoid in there, who was on to something). You see captain Janeway being destroyed by a beam only for an incredibly equal copy to emerge just besides you and you end up believing you'll be ok. So you'll beam yourself too. But those will just be the last few nanoseconds of your life.
This idea that you are just your current brain state and nothing else is interesting. Many difficulties start happening once you start questioning it (how far back in time must I go to say it's not "me" anymore?), and its weakness comes from purely taking the mechanical approach to consciousness - "Consciousness is just the result of a program running in the brain". An analogy as faulty as the one made a hundred years ago (that the human body was akin to a steam engine, and thus should let go some "steam" once in a while). Again, it is an interesting idea and one that might well be true (I really don't think so). I have no idea if it is true.
But to blindly accept it as such and declare the denial of it as something delusional, is just an intellectual overreach for the sake of philosophical edgelording IMO.
And even if you believe in it, just the possibility that it is indeed false (and the impossibility of knowing eitherwise) should render your decision as clear as day: Never teleport. EVER.