Trump is above all a smart business man that is focused only on a few things: Making more money and possibly increasing his overall power.
Power does not have to be from being the President!
I have serious doubts that he believes he can win the Republican nomination. But he can increase his power/brand and make more money if his strategy is the following:
We already know that he is not close to any of the Republican candidates. But based on attendance to his last marriage he does have a relationship with the Clinton's. Who really benefits from the Republican nomination primary battle with Trump leading the polls?
I can only think of Hillary. Could it be that Trump has an understanding with the Clinton's that would favour their win and his business? Simple strategy but very effective when you have a 'friend' in the White House. He becomes the main power broker that helps his business and gives him more power. The Clinton's on the other hand get a good ally that gave them victory.
Even if Trump ends up as an independent Hillary wins anyway.
Think about it! It would not be that surprising....