>I don't understand why people don't get this simple fact.

Some people think identity and the continuity of consciousness are based on information or computation, and not on specific physical matter or soul-like constructs, so for them a transfer of all relevant information would constitute a transfer of consciousness and identity. From this perspective (leaving aside questions of practicality) "you yourself looking from the biological body at somebody else in the computer" is exactly as valid as "you yourself looking from inside the computer at somebody else in the biological body" (and in fact the whole idea that you have to choose one or the other as "the real you" becomes moot on this view).

Of course it's a difficult metaphysical conundrum but to say that your view of things is "a simple fact" when the basic scientific materialist worldview of today points at least as much in the opposite direction is a bit overconfident.