Transporters work by de-assembling something (e.g. you) and re-assembling it somewhere else. What if, when you’re dis-assembled, you die, and the re-assembled version of you is essentially a copy? Then every time someone steps onto a transporter, their final thought before death is that they’ll end up beamed somewhere else. And the re-assembled version (copy) just thinks that everything went fine and continues on like nothing bad happened.
If you arm gets cut off, you and your arm go together to the hospital, and they reattach it, are you a different person? If you die in the ambulance and they revive you, are you a different person?
More like: If you replace all parts of a boat with completely new parts, is it still the same boat?
Well no, it’s the same parts. It’s literally called the matter stream. The exact same parts are taken apart, moved to a new location, and reassembled.