Perhaps a condescending take but I think the author got a bit of a big head from getting promoted quickly, and the subtext is that it was due to their amazing technical competence. It’s a noteworthy feat to get recruited out of school, but SRE is a godawful position with high attrition, so it’s easier than SWE to get promoted. That they regret not moving to SWE sooner ignores that SRE is a talent sink and considered a separate ladder by most companies. At this point, the ship has sailed. Eat humble pie, embrace your skillset, and move onward and upward