Top 5 gets bumped up to a new level every year. An educated guess - a one time commitment of $30-50M to catch up to the top 5 and then ongoing $5-10M infusions every few years to keep up.
The stadium is a magical/timeless experience. Incredible atmosphere, especially when the product is right. But if you want it on the top level there’s a big gap of some things we’re missing in the concourse, entrance, seating, capacity, outfield seating, suite, etc. and I’m not sure you can change the orientation of the stadium to fix a lot of it to that level
I’ve played/camped in 9 SEC stadiums (TN, SC, UK, Auburn, Alabama, LSU, Missouri, Vanderbilt, Georgia) and I think 6 ACC stadiums (Miami, UNC, NCST, UVA, VT, and GT). Granted, these were anywhere from 9-15 years ago, Miami was near the bottom of that list if I was ranking it unbiased. All have changed since then. Lindsey Nelson (Tennessee) was a **** hole my entire life, easily the bottom of my list of those 15, below Miami at that time, and now it’s getting bumped into the top 5. I would guess Miami is in the 25-30 range. Higher if you value tradition and novelty and not just flashiness.
It takes winning and commitment. Even when we were winning, like football, commitment to facilities and infrastructure wasn’t there.