Everything has an economic cost, even if there are benefits: this is known as opportunity costs, or cost foregone. So, what are the costs of open borders?
https://www.zerohedge.com/political/open-borders-are-trillion-dollar-mistake
“As I first read Bryan Caplan’s “Open Borders Are a Trillion-Dollar Idea” in Foreign Policy, besides disbelief, my thoughts were that this person must not get out much or must not read much. A quote from writer Upton Sinclair came to mind as well: “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” What is Just? “Open borders are not only just but the most promising shortcut to global prosperity,” writes Caplan. This raises the question of who determines what “just” is? Just is not a defined term that someone can easily review (as Caplan seems to imply) and determine whether a particular policy is just or unjust. In fact, each individual probably has a different definition of what just is. But in the United States, I believe the vast majority of citizens see Open Borders as a totally unjust policy. It is unjust because it is generally accepted that the population of a country has entered into a social contract with the leaders and government of a country. Under this contract, the population will follow the rule of law, and the government will pass and enforce policies that have beneficial impact upon the population of the country. There is no social contract between the leaders and government of one country and people who live in another country. As an example from across the pond, the new Italian government recently released figures showing that the state will allocate €50 million next year, €200 million in 2021 and €300 million in 2022 to the Disability and Self-Reliance Fund of Italy. Some 2 million disabled in Italy rely on these state benefits, which work out to just 54 cents per day in welfare – insufficient for even a subsistence diet. In contrast, Italy is providing migrants €20 euros a day. Most Italians are likely to see this policy as unjust. Similar per capita spending differentials exist in funds furnished to needy citizens and migrants in the United States. That is also unjust! What Missed Opportunity?

