There are many possible reasons. For example lower cost of living, retiring in a place that has both lower costs and perfect weather or moving for business reasons only etc etc.
It happens even on a very micro scale when people move from cities to villages or the other way around. I quit a city life and moved to a village (~1200 inhabitants) but I also changed as many habits as I could to enjoy this life style. I met a lot of people early on and got to know them, developed some friendships, helped out and got some help. They are (edit: I would dare to say: we are, I feel part f the community now) very open, honest and inviting if you are as well. However there are people who move purely because property is way cheaper, but they want to maintain their city lifestyle and then try to contest the aspects of rural living that interfere with their idyllic vision of peaceful and silent sanctuary away from all civilization. There are noises and smells, tractors and cattle. Infrastructure is not up to par. Shops close early. And, worst of all, some treat the locals as uneducated dirty mass that is below their middle-class level. They tend to isolate and only seek company of other "expats". And in consequence are treated as suspicious, or even unwanted, element by the locals. It builds tensions and happens on the scale of ~50km between a village and the nearest city. On international or intercontinental scale it is probably amplified by orders of magnitude.
It happens even on a very micro scale when people move from cities to villages or the other way around. I quit a city life and moved to a village (~1200 inhabitants) but I also changed as many habits as I could to enjoy this life style. I met a lot of people early on and got to know them, developed some friendships, helped out and got some help. They are (edit: I would dare to say: we are, I feel part f the community now) very open, honest and inviting if you are as well. However there are people who move purely because property is way cheaper, but they want to maintain their city lifestyle and then try to contest the aspects of rural living that interfere with their idyllic vision of peaceful and silent sanctuary away from all civilization. There are noises and smells, tractors and cattle. Infrastructure is not up to par. Shops close early. And, worst of all, some treat the locals as uneducated dirty mass that is below their middle-class level. They tend to isolate and only seek company of other "expats". And in consequence are treated as suspicious, or even unwanted, element by the locals. It builds tensions and happens on the scale of ~50km between a village and the nearest city. On international or intercontinental scale it is probably amplified by orders of magnitude.