It’s true that the entirety of a person is “just” a very complex interplay of elementary particles, but I don’t think it’s only an actual issue if you’re a spiritualist. I’m a naturalistic determinist, there’s no such thing as souls or spirits.

My line of thinking is this. Let’s say I step into the machine, and it makes a perfect copy of me at another location, but fails to dismantle my body. Since we’re talking about the transporters in Star Trek, there is precedent for this happening. I step out of the transporter entrance, and another me steps out of the transporter exit. I don’t see through that person’s eyes, I don’t hear through that person’s ears. They are separate entity, no matter how similar they are to me.

If the transporter had successfully dismantled me, I still wouldn’t see through that person’s eyes or hear through their ears. I would be dead. Another person with my memories would step out of the exit. As far as the rest of the universe is concerned, that person is me. But I don’t care about the rest of the universe, I care about my own brain, which has been destroyed. Why would I agree to be transported, if I don’t get to see what happens after?