When looking at the potential impact of immigration on global wealth, we must consider the costs. Few economists argue that if everyone could move to where they had the best economic opportunities, the world GDP would increase by trillions. When considering the boost, the pivotal factor is R, the ratio of first-world to third-world salaries for equally skilled labour. If R=2, where an immigrant’s salary would double after relocation, the world GDP would rise by $9.4 trillion. On the plausible high-end, R=6, and world GDP would almost double from $70 trillion to $132 trillion.

To know the net increase, we need to know how much it would cost for relocation. The proportion of those that would move are people who would take a wage cut because they feel unsafe or insecure in their current country. The vast majority of potential migrants would place a far lower value on staying put than the average Westerner, for whom the psychic and opportunity costs of moving are more considerable. Also, as more people move, the psychic hurdle of moving will decrease because there will already be more migrants in the destination. Here, we see the gains for an individual considering relocation, and thus increasing world GDP, are almost certainly outweighed by the personal benefits of higher living standards.