30 _high school_ stadiums at 10000+ I can’t even fathom!
That would be the equivalent of having the top 6 teams in England's Premier League -- which based on last season would be Arsenal, Manchester City, Manchester United, Aston Villa, Liverpool and Bournemouth*
College and High School are more like the equivalent of national teams in England, although in America is seems that the taxpayer pays for these, where in the UK they are private businesses.
* There was a coup attempt a few years ago by a bunch of european teams to leave league football behind and make more money, because in the uk "only those 6 teams win". Chelsea and Tottenham fancied themselves, Tottenham narrowly avoided relegation and finished 17th, and Chelsea were topped by such internationally famous teams as Brentford, Brighton and Bournemouth