I think everyone have heard about Sir Isaac Newton who discovered the Laws of Gravity (Newton's Law) in the 1600s. From his discovery, it revolutionized astronomical studies. But, if it weren't for Edmund Halley, Newton's idea might not be learned by anyone.
Then, who is Edmund Halley? Well, you can say that Halley is the 'backstage' for Newton's success. He helped Newton's from many aspects, he challenged Newton's assumptions, he corrected Newton's mathematical calculations when there were off and also supports Newton's work with his own drafted geometric diagrams. More than that, when Newton reluctant to publish his work, Halley convinced him to write the manuscript where he himself then finance the printing of the manuscript. Then there is where the final work of Newton's was publish, 'Mathematical Principles of Natural Philosophy'. With this, Newton's became one of the most highly regarded thinkers in history.
Self Promotion and Selfless Promotion.
Halley knows that no one can actually work alone. He decided to support Newton from the 'backstage'. If not because of him, Newton's might not been known today. His objective is for all to learn about Newton's finding. He can always lift himself so that people know him. But he did not do that. This is what it meant by selfless promotion.
On the hand, there are people who lift themselves among the others so people know them. Their objective is more towards their own benefit rather than for the team Worst of all, they rather stab their own friend for their own benefit.
If we bring both kind of promotion together, to be in the middle is the best option. I don't think that self promotion is wrong (not back stabbing off course). There are times where you need to lift yourself. We just need to know when to self promote and when to selfless promote.
Anyway, always remember, that working as a team, you must always have a desire to win as team but lose individually, rather than win individually but lose as a team.