Well, if he's that bored, why is he running for a second term?
I think he likes being the center of attention surrounded by adoring fans and he does things like this to keep those fans entertained. That may be the motivation behind becoming president and wanting another 4 years. To him the presidency is just for show. More reality tv -- a medium for which he was famous.
But he never really had any interest in actually serving as president -- performing the duties inherent to that position and keeping his campaign promises. He doesn't give a flying fig about you, me or the rest of the country. He just wants to be famous.
With all that being stated, why then did he run?? I have come up with several scenarios;
He saw a huge hole in the GOP with a bunch of disgruntled voters with the establishment and the issue of illegal immigration and the wall, and saw an opportunity to make a whole lot of money. He jumped into the race and gave it his all, never really expecting to win, but one he won the nomination it became serious business to him.
With liberal ties, especially to the Clintons, he was merely inserted into the race to take out Bush who was hailed as her biggest rivalry and conservative Cruz, paving the way for his friend Hillary. Once he won the nomination and realized his popularity, he wasn't about to hand things over to Hillary. In her eyes and in the eyes of her supporters, he stole the election from her. He in return has protected her and helped to cover up her corruption.
Incidentally, he has announced he is running for re-election. If he truly had no interest, I think he would have announced he wouldn't be seeking a 2nd term.