Respectfully, I gotta argue with this here. This concept is uniquely modern in the U.S. and is a misconstrued understanding of certain oriental ideals. Historically speaking, modesty and humility didn't get you jack squat as a martial artist. You depended on your martial arts skills to earn a living either through successful fighting or through attaining students (the richer, the better). Neither of which were enhanced in any way by modesty and humility. Thus, historically speaking, in almost every culture, a master of martial skills wanted everybody to know about it for the same reason that an College Football coach with a championship season or an NBA star with a free-throw record wants everybody to know about it. You get better jobs, more money, cushy setups, students, and patrons.
Further, the ability to fight well is pretty much decoupled from modesty and humility as evidenced by the number of absolute douches in the top level of pretty much any combat and combat sport, everything from boxing on out. In fact, extreme high levels of confidence and "positive self image" is both a requirement for performance success and tends toward incompatibility with modesty and humility.
Peace favor your sword,
Kirk