How did you learn distributed systems development?

I got basically thrown in the deep end as a sysadmin in the old days. I probably saw more “counterexamples” than well architected systems early on. But you learn real fast when the org decides that you should somehow be the expert on how all the miscellaneous pieces fit together after years of abandonment

Combination of study (books and papers), and a few senior devs who were deeply knowledgeable and generous with their experience.