As another commenter noted, it really depends on what you hope to achieve in your career, but it's rare that an 18-year-old has that figured out. I'm in my late 20s and haven't figured it out!
Ultimately, the main thing Tier 1 university gives you is a foot in the door. For 95% of non-savants, the educational experience is the same, if not worse, than your "Tier 2" schools. There are many other (much cheaper!) ways to get the type of prestige which opens doors: Y Combinator, Recurse Center, an internship at a prestigious company, certifications, etc. That being said, prestige only opens the door -- you'll still need to kick it down.
Think of it this way: you are being given ~$300k to go to school. This is the same amount of money you would earn after working full-time for ~5 years after factoring in taxes. You could literally travel the world for several years and come out with less debt than paying out-of-state tuition for four years at UIUC.