Been doing this for nearly a decade, mid-six figure income. No employees, no customers to deal with, just content that I update on a weekly basis, with links to high-quality affiliates that I trust and actually recommend.

Anyone who can write a decent book on a subject that consumers care about can do this, but it does take time, probably a good 3 or 4 years before you start making decent income, would need to start it as a side project while working full-time, but I'm convinced any decent writer can do this.