when I looked at the billion-dollar companies in my study, I unearthed a compelling pattern. Almost 60 percent of those founders had previous experience as startup founders. Not as early employees of startups—but as founders, and in most cases as founding CEOs. Some of their prior ventures were massive successes; some were catastrophic failures. The thing that seems to matter is doing it more than once.
I occasionally add a personal note to them.
The whole collection is available here.