I agree with these points. I think although the three students experienced imposter syndrome often, wondered why they became clones, and questioned who they were cloned after, they were more scared to leave their situation. Although they were unhappy and knew their fate, it seems that they still somehow accepted their reason for existence. This ending feels like it was specifically chosen by the author to invoke strong feelings by the reader and make the reader see the scenario of a sad ending. I don't think we, as readers, would have the same strong feelings around human experimentation and have these same conversations if the students successfully escaped and live happily ever after.