It really would not be hard to enforce it. There are plenty of security/arena employees to roam around and ask people to put their masks on or leave. While the people that attend may not be worried about getting Covid, it would be nice if they also cared about giving Covid to others - including other fans, athletes, and coaches.
Most people wore masks in the hallways and other open spaces, but took them off or didn’t wear them properly when in their seats. While I am not particularly scared of getting Covid, I am also trying my best (within reason- I went to Senior Nationals (wearing about N95), eat at restaurants that practice social distancing, etc.) not to get it or spread it.
When people attend and don’t wear masks at events like this, they kind of ruin it for everyone. I cannot see how the NCAA will allow fans in an indoor arena when people won’t wear masks. Could you imagine having fans at the Big Ten Tournament that don’t wear masks and turn it into a superspreader event and infect many of the wrestlers - who are then not able to wrestle at Nationals?
I am not a big alarmist, but I would like to watch wrestling in person. When people won’t wear masks, that isn’t going to happen.