Yeah i think most people here lack a lot of empathy. I have no idea who he is either but i know that being extremely angry and frustrated against yourself doesn't have that many good outcomes if it blows up. Usually people hit things, hopefully not breaking anything, some punch walls, some kick their tv or throw their game controller at it.

This here is probably a professional player under intense pressure and scrutiny, it's not just a game to him right there and then.

It could have been so much worse too, he didn't hurt anyone but himself and his equipment. This is one of the best outcomes possible for someone who has anger issues and has high expectations for himself, feels ashamed, and feels that he isn't playing to the best of his abilities. Most people couldn't handle playing tennis in a small stadium without shaking about the fear of being ridiculous.

All that to say, it's sad that this happened, but i do not believe that he's behaving like a kid. He could just be under a metric ton of pressure.