Successful one-person online businesses?

This question was asked last year (https://news.ycombinator.com/item?id=21332072) by gajus, and I'm curious what it looks nowadays.

How many people on indie hacker are running successful online businesses on their own? What is your business and how did you get started?

Defining successful as a profitable business which provides the majority of the owners income.

Has recent shutdown of economy affected your business?.