I think he’s referring to the 80/20 law, or Pareto distribution.

Essentially 80% of all corporate output is performed by 20% of the workforce, and continues down each chain (of the 20% doing 80% of the work, 20% of them are doing 80% and etc…)

https://en.m.wikipedia.org/wiki/Pareto_distribution

https://www.americanexpress.com/en-us/business/trends-and-in...

I would say that for the first 10 years of my programming career I was not competent. The next 5, I was marginally competent.

I like this essay on the topic:

http://www.norvig.com/21-days.html

What bastion of skill did you work at to think it's a higher percentage? 20 sounds right to me, maybe even lower.

I think what they're implying is that the bottom 80% are incompetent and should (presumably) feel bad. This is an interesting way to define competence.

A few years in any professional field like software engineering is enough.

Experience with humanity? Dunning-Kruger, Peter Principle, hubris, and just plain laziness compound nicely to make 20% seem like the right ballpark. There are a lot of people out there who are not very well suited to what they do, often through no real fault of their own. I don't think it's toxic to recognize that.

In reality it's probably more like 0%...