John McEnroe acted bad back in the day
Ilie Nastase made McEnroe look like a choir boy.
For McEnroe it was schtick. People watched his matches just waiting for him to explode on a linesman or other official. It’s like the fans that go to a hockey game to see a fight. In Serena’s case, she was losing and the on court drama was meant to distract her opponent and give her an entrance back into the match. She is also a big phony with her “so nice” press conferences and interviews. She is a nasty, egotistical person whose real character surfaces on occasion and it’s not pretty.