For most people trying what you propose, making money while traveling, is not possible. Luckily, there are plenty who prove this just a rule of thumb, not a hard law.
Yes, it's possible to make enough money from a vlog, a blog, photography, professional articles or travel advice. But it's very hard to get started, and no real shortcuts to make it big. From my experience, it's really almost always a bit of luck and a lot of persistence that make for success.
That said, if you're indeed a decent developer, going freelance will allow you to be quite mobile. Perhaps even mobile enough to travel a lot. But what then helps is an existing client base who are ok with not always, if ever, meeting you in person.
I travel 3-6 months out of the year and have lived in a dozen countries or so in the last 15 years, pretty much always project related. I'm a developer. So, I'm not too distant from the type of life you seem to be interested in. But also know that the first half dozen years were rather tough. I got out of a well paying job to earn virtually nothing for years. But, I also firmly believe in the end it was worth it.
Pretty much all the projects I get are through word of mouth, which seems to be often the case when you're a freelancer, whether you're on the go or not. In the end, I'd say that keeping your client base happy or finding new clients isn't much different whether you're on the road or not. That said, clients tend to be wary of working with providers who they can't see or call into their office once in a while. The only remedy for that, really, is to consistently deliver quality.
Indeed, health care expenses outside of the US are reasonable in many places. International health care plans that don't cover the US, but pretty much do cover the rest of the world are often reasonably enough priced. And worth the money, in case something goes horribly wrong.