Everybody is different. Philippoussis had a lot of talent but he also liked to ride fast bikes and fast women. Does that make him dumb? He made his choices an had a lot of good times.
A lot of people who post on this site will be making tennis 100% of their lives. Most or all of them will fail to make any impact, and will insult players like Philippoussis. Philippoussis made tennis only partially important in his life, yet had a lot of fun - plus a few tennis highlights like playing Federer in a Wimbledon final and winning a few titles.
I know who I'd rather be.
Anyway the guy was injured and had some bad luck too. Wasn't he even in a wheelchair for a while?