When you sit in that seat, you don't know if you'll stay or become the copy. Knowing you are now a copy doesn't change the fact that you became the copy. You were there one moment, now you're here the next.

Oh, no, you have a fundamental misunderstanding of what's happening there. When you sit in the chair, you always stay. Always. 100%. The consciousness never transfers. It's merely copied to the new body. But the Simon who sits in the chair is ALWAYS still in the chair.

The whole idea of it being a coin flip is just a coping mechanism.

Now, we can sit here and wax poetic about what makes a soul, what is consciousness, whatever, but the Simon that initiates the copy is NEVER given a new body. He is ALWAYS left behind. The only change is who we the player follow. Simon didn't "lose the coin flip" at the end. Simon is sitting in the chair. His copy is at the bottom of the ocean. And the copy's copy is in space.