Out of the 3 businesses they name, 2 are abuse based businesses. Park.io is for-hire domain-swiping, closet tools is follower and social network automation and spamming tool ...
Best way to start on the path to building one of these businesses is to start building a following. Many of these 1 man companies are reliant on strong founder personalities that develop a following. Makes distribution way easier.
This seems absolutely important
These are solo founder businesses. Many of the examples hired employees. If you have a boring b2b SaaS that charges $100 a month, you only need 1000 monthly customers to gross $1M a year. You don't need a personality, you need a decent funnel.
Assuming B2B. Can one individual manage the demands of 1000 clients?
No. If you look at the article however, many of the examples have employees.