Naruto is confident in his abilities and of becoming Hokage because these can be achieved by his efforts alone. Love doesn't work this way does it? It depends on the other person. Self confidence won't help much.
I agree with this in principle, but self-confidence does help in several ways. Being confident in himself -- despite much of the story when he couldn't actually prove it -- is a hallmark of Naruto's character. 
For a guy so confident in everything else he does, Naruto's blatant insecurities over Sakura's reciprocation never ceases to amaze me.
If Naruto were not a self-confident character he would never have set and kept his sights on Sakura in the first place, nor made as many attempts as he did to get her attention and ask her out. He obviously believes he is or will be a worthy suitor, that he has or will have what it takes to win her heart, and that he could make her happy.
The way I see it, Naruto was a kid working his way toward greatness -- to be the strongest ninja, to become Hokage, and just general coolness -- a side benefit of which would be so he could impress Sakura and compete with her interest in Sasuke.
But then his motives changed, right? When Naruto realized how much Sakura really loved Sasuke -- that it wasn't just a flirtation or something shallow -- he set aside his own love for her to help her get HER love fulfilled and made the PoaL.
It was never about a lack of confidence that he thought Sasuke would always be better than him when he was finished attaining his great skills and recognition, or that Sasuke was in any way better for Sakura. It was because Naruto recognized Sakura's feelings and loved her enough to try to make her wishes a reality. One thing that had been made clear since #3 was that part of why Naruto loves Sakura is because he understands the depth, passion, and motivations of her heart.
Even during Sakura's confession, Naruto's reaction didn't strike me as lacking in confidence. Quite the contrary. He was extremely grounded and realistic. He was angry with Sakura because he thought she was lying to herself about her feelings for Sasuke, and rightly so. He had the confidence to not want her love unless she gave it freely and for the right reasons.
The key thing is, I think, that Naruto doesn't want Sakura to not love Sasuke. He loves Sasuke himself, after all. He wants Sakura to not be in love with Sasuke, and to be in love with him instead.
In my opinion, it takes a crapton of self-confidence to be in that situation and still maintain positive feelings for both Sakura and Sasuke. I mean, think about it. Naruto never gives up. Part of bringing Sasuke back was not just because it would make Sakura happy, but if Sasuke didn't come back Naruto could never stand next to Sasuke as an equal and properly vie for Sakura's love.
I don't think Naruto will be satisfied with the triangle conclusion until he knows Sakura and Sasuke are at peace with each other, and that despite having an opportunity to pursue a reformed Sasuke, Sakura chooses Naruto instead.
Just my opinion.