Humans are competitive creatures, we always like to move forward in life. Comparing self progress with others is one way to keep the competitive spirit alive, other is to compare self progress. The comparison of self progress usually is with respect to time and position. Over the years, I observed that each year I think I slightly improved myself as compared to last year. This happens almost always, if I do forward interpolation of this thought; I realize that even though I am better than last year, I am stil preparing myself for the next one. In other words, I am better than last year but probably not as much I would be the year next.
Other observation I made is everyone has role models, and these role models also have their role models. This chain keeps on going, it may or may not be circular, but chain keeps on going. Simply put, at each point in time, almost every determined person has a place where he wants to be and where he currently is with respect to time. Considering the betterment of a being as upward progress, we can imagine the entire human community split in herds and standing on mountain slope. The herds above your position are where you want move eventually and herds below you is where you have been.