I have done that for years now, but honestly, it gets tiresome having one foot in each country and nowhere really feeling like home or reflecting a whole life. Financially, it is also more expensive than just settling down in one place in Thailand, paying the tax, and keeping or transferring whatever your visa requires. As long as you are mobile, it can work. But there comes a time when travelling becomes more of a hassle, especially if your health starts to decline. And if someone is already on a tight budget, six months here and six months there does not necessarily save much money anyway.