Several years ago A&M played Louisville at the Music City Bowl in Nashville (2014 or 2015 I believe). My wife is a big Chris Stapleton fan, so we went for the game and New Years celebration on Broadway. CS was the #2 guy and local stars, The Kings of Leon were the headliners.
We wanted to be decently close for the CS portion of the show, so we got in a little early and waited around as other concerts played on the main stage (in front of us) and the second stage (behind us). When CS came on there was a huge rush of people pushing to the front. We just kept getting squished tighter and tighter, with nowhere to go.
Midway through we decide we've had enough and try to leave. As we start pushing our way to the back of the crowd, things got tighter. At one point it felt like you could lift your feet and you wouldn't fall. Women were crying, people looked ready to pass out. Guys were fighting. It was hot in the crowd, but 30* outside. We eventually just put our back into it and fought our way to the outside of the mass.
The city estimated that there were over 200k people in town for NYE, and most of those people were on Broadway for the concert, music note drop, and fireworks. After this experience, I can absolutely understand how something like what happened at Astroworld would go down.