Granted but everything I have read suggests that Nole (and his family) have pretty much devoted their lives to his tennis career and made significant sacrifices along the way. He had (well until recently) always stated his intention to reach #1. So, having put in those years of effort, I would have thought he and they would be disappointed if he gets sidetracked by the err...benefits of fame and doesn't make the most of his chance at the top now it has come.
With the increased physicality of the game, most players these days peak in their early 20s and slams after 25 will be increasingly rare. So once he's 25 or so he can party himself into the ground and shag everything in sight.
Having said all that, I am talking out of a dark place here and am certainly not in any position to criticise; I have always lacked motivation and am pretty lazy myself.