Missed my point & I'll admit I could have presented it more clearly. He may be a great guy in his personal life. You're right, I don't know him personally. However to me, for people who are so much in the public eye, "greatness" comes with other qualities of behavior.
This is an extreme example only to illustrate where I was coming from: I didn't know him personally either, but I admire and think of Martin Luther King, Jr. as a "great" human being. Not because he was wonderful in his personal life, but because of how he treated all people when in was in the public eye.
To my view, Shaq will go down as a great NBA player. That's hardly arguable. He may also be considered a "great human being" by those who do know him personally, that's for them to decide. But I think in some of his public behavior, he has chosen to act far below what I consider a "great" human being in terms of someone to admire and hope to emulate.
I am entitled to my opinion on that measure of overall "greatness" of a public figure.