It actually does depend on what rank you are on how strong you are. When you're a Genin and Chuunin or even an Academy student, you work harder to become stronger, and once you reach Jounin in a way you have proven that you are strong by lasting that long in the game and ranking up, so that is why most good things are for higher ranks. Even for Jounin, there are still things we have yet to achieve, as for me, I'm a Hunter Nin, trying to reach Sannin so I can see Hoshi Gakure. We all want to become stronger, simple as that.