That's... not actually how that 30/70 statement is meant to be read. Imagine as a simplified analogy, applying to get into Harvard. Imagine Harvard has 1000 sp

That's... not actually how that 30/70 statement is meant to be read. Imagine as a simplified analogy, applying to get into Harvard. Imagine Harvard has 1000 spots to fill, and that there are 10,000 applicants with roughly equivalent credentials (because they all have: near perfect test scores, high GPAs, strong extracurriculars, etc.). In that environment, one might conclude that, for people who successfully get into Harvard, it was 30% their own skill, and 70% "luck" that the they happen to be semi-randomly picked by the admissions committee who could've easily gone with a nearly-equivalent alternative. So sure, in that environment, "luck" is a factor, but this is by no means a "free lottery ticket" because the near-equivalent applicants had to work hard and be smart to reach the point of being near-equivalents of each other... So it is with promotions in competitive tech companies at least, where good talent is the norm.