He was.
I mean, the guy was famous (he still is) but despite the fame and fortune, opportunities to meet powerful people, millions of fans and travel around the world, have the people's eyes and ears on him, there was something missing, and that "missing" thing made him the sad person that he became. That "missing" thing was unfortunately what he wanted. Badly.
I guess he just sought that work-life "balance" in his life--make music on one end (work), but have a life "out of it" on another. But he (somehow) did not get the latter, because when he tried to do so the work always followed and chased him.
MJ sought for the simple joys in life, which he somehow (or did not at all) was not able to experience. Go out of the house, say hi and smile to random people without getting mobbed, sit on a park bench and observe people, talk to and learn about the "normal" surroundings, etc. The guy has a lifetime of singing, awards and public attention, I guess he just wanted that opposite of those for a change.