Good at self-promotion == just good in most cases for most practical purposes whether it's factual or not, arguably. His books seem substantial though, I don't know many people who've read or written 800 pages on system performance

> Good at self-promotion == just good in most cases for most practical purposes whether it's factual or not, arguably.

This does not seem true to me. Most popular programming YouTubers are demonstrably great at self-promotion but tend to be mediocre or bad programmers who know very little, even about the topics they talk about.

If anything we have plenty of examples of where being good at self-promotion correlates inversely with actual skill and knowledge.

With that said, I wouldn't classify Brendan Gregg as being good at self-promotion.