简单回答： 这是一个原则问题。 没有军队，就没有国家。同理，没有边界，也就没有国家。

问花钱建墙值不值和花钱养军队值不值是一样的道理。 我们花在他们身上的净支出是多少? 下面有统计：

total cost of illegal immigration at $135 billion a year, while claiming undocumented immigrants paid only $19 billion a year in taxes. That leaves a net cost to local, state and federal governments of $116 billion a year. 

https://www.azcentral.com/story/news/politics/fact-check/2018/06/26/paul-gosar-how-much-do-undocumented-immigrants-cost-economy/691997002/

所以，建墙还是值。