It took me about 2 months to get a self-employment residency permit for Sweden. While I looked around for lawyers to help, I couldn't find any, and ended up writing it myself. It seems very few people do that option.
YMMV of course. Which is my point.
But as for the other parts, it depends on the type of person you are and what you want. I did the 3-month-at-a-time tourist visa option for a bit over a year. (It's not quite a 'visa run' because it wasn't a cross over the border and back thing.) It got tiresome to start make friends and then leave them, then come back, only to leave again.
On the other hand, there are people who do that for decades, and love it.
While I sell software, my customers are businesses, in a market where most contacts start by meeting people and word-of-mouth. Most of the people who might buy are in the US or Europe, and that's also where most of the conferences are held. It's much more expensive to send my bundle of atoms from South Africa (one of the places I considered living) than from Sweden.
Again, this isn't true of everyone. There's a big difference between "and start bringing in a few hundred bucks a month from paying customers" and my software, which sells for a few tens of thousands.
It also becomes harder if you want to have access to a local user's group (I co-founded the local Python user's group) or makerspace.
So if your interests are surfing, rock climbing, Swedish women, and beaches, and you are selling direct to customers who expect no personal connection, etc. then certainly living overseas can be a great idea.
I do believe that living or even just a multi-month travel overseas is a good thing to do at least once. Just bear in mind that it's not always as rosy as this author paints.