I feel like this "get ready to be surrounded by peers for the first time" or the related "you aren't used to working hard, but now you will actually have to work hard" speech was given to me in some form at the start of high school, college, grad school, and in many other contexts and intermediate milestones. It wasn't ever completely true, but I think if I went for a PhD it would (obviously) have finally been true.

To be clear, I'm not saying I was always smarter than people around me, I just felt like I never had to work as hard as I suspected even through my Masters program.