This is simply not true. I went to what I would call a tier 3 school for undergrad and then ended up at MIT for graduate work. The difference between the two institutions was really night and day. Not only are the classes more rigorous and the instructors objectively better at MIT, but the students just think differently: they have much more ambition and are far less constrained by the status quo / what their parents did. Being around that totally changed my outlook of what is possible and what I should expect from myself, and really pushed me to make huge career and self-education strides.