unless you already have very good global coverage insurance, why would you not want to get yourself covered in Thailand? I've read of many who got into serious accidents and there was no insurance and the family has no funds to expatriate the patient back. And if you already have global coverage, you can use that for the retirement visa, don't have to purchase a local one.
a lot of digital nomads don't pay taxes because they don't live in 1 place long enough but they enjoy the infrastructure that the taxpayers of that country provide.