Most countries (at least here in Europe) have very high taxes, so whenever you go, you'll pay pretty much the same. So if people move, they do it for what they can get back for the money they pay. However the problem is that the system is setup so that it penalises ambitious people while protecting the rich. In many countries the governing parties see people as their clients and in their interest is to keep everyone dependent on benefits or being on the verge of needing them. That's how you game democracy and as a side effect you severely inhibit growth. (Good example is how little "unicorns" Europe has)