Engineers, of which I am one, tend to see the world in pure dialectics, so they often have very difficult time understanding why accomplishment is not purely evaluated by some rational universal force and recognition made manifest commensurately.

Self promotion is a skill that we all need, and do not think for a moment that people like Einstein were not well skilled in it.

As for claiming credit in higher proportion to one's contribution, that is evil in proportion to the exaggeration. However, perception being limited as it is, no one, not even the other contributors are in a good position to judge.

As for outright lies, they are, well, outright lies.