A solopreneur hits a ceiling. A company of one does not have the same one.
The difference is structure. A solopreneur does everything personally. A company of one has departments, and the departments are folders that an AI operates while the operator judges.
The distinction that matters
Doing everything yourself means your output is capped by your hours, and no amount of tooling changes the shape of that limit. Having roles means the work is organized as if a team existed, with each role's craft and procedures written down, and the operator moving up one seat from doing to deciding.
This is not a claim that one person now equals a team. It is a claim that the structure a team provides can exist without the team, and that the structure was doing more of the work than most people assume.
What you build first
One role, taken to the point where it is genuinely reliable, before a second is started. The gate before replication is the single most important discipline in the install, because copying a role that is only sometimes correct multiplies the incorrectness.
The book's install path is 90 days and paced for somebody with a business to run rather than a free week.
“I don't write code anymore.”
The honest ceiling
No documented case exists of a one-person billion-dollar company. The prediction is on record from people close to the models and it remains a prediction. What has changed is the ceiling on what one operator can run, and that is enough to be worth building for without overstating it.