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.
It goes a lot farther than that, actually. If you have the technology to assemble a person on a molecular level like that, you can basically prevent that person from dying. Captain got killed by an alien on an away mission? Just print another copy of them from their scan from just before they left.
Pretty sure that's why they specifically talk about how signal degradation occurs over time in TNG. You're not supposed to be able to keep somebody in the buffer for an extended period of time, or you'll lose the signal. This has been retconned multiple times though.
But didn't Scotty store himself in the buffer for a ridiculously long period of time?
Edit: I just looked it up, and in the episode of TNG "Relics," his shuttle crashed into the Dyson sphere on its way to his retirement community. With no supplies and little chance of rescue, he stored himself in the transporter buffer for 75 years until his crash was discovered.
Yep, that's one of the examples I was talking about when I said they retconned what O'Brien said. Although this specific example, they play it off like Scotty did some crazy tech to create some sort of feedback loop to keep his signal from degrading for like 80 years if I remember correctly.
There's also an example in strange new worlds, Dr. M'benga is keeping his daughter in the transporter buffer in the medical wing. There's also that one episode on TNG where Barkley found all those people who were trapped in the buffer thinking they were like interdimensional worms or something.