Why do people "break the law" to come to the US, and how do their coming affect you negatively? And again, H1-B is not an immigrant visa, I don't see why you're talking about it here.
They are economic migrants without the means or desire to immigrate legally.
> how do their coming affect you negatively?
They depress blue-collar wages for my fellow Americans. They increase competition for housing. They increase the burden on services like medical and education. I could go on and on...