Not affiliated with this site in any way, but Indiehackers shares many examples of people doing exactly this: https://www.indiehackers.com/businesses
Plus the freedom is worth thousands alone in my opinion, if I have the choice I'll never go back to startups. It seems like startups are the default these days, and so many of them would probably be just fine as regular small-medium businesses. I have to cram the idea in people's heads haha, you can make money in software and not be a slave working 14hr days.