First off, there is a difference between “I come from a decent country and therefor have no real reason to take the risk of illegally immigrating somewhere” and "My country is very, very bad (possibly in not small part due to country X), and moving to country X illegally is less risky for my life and family than staying here". We tend to have at least some empathy for people in the second scenario.
But even never minding that, you could say a lot of things : The U.S.A is a country literally built by immigrants. The native-american are a minority in their own land. So is it surprising that a lot of people in an immigrant country support immigrant ? Then, there is the dirty economic secret that illegal immigration fill the low-wages jobs that citizen don't have to lower themselves too. A lot of ties, rule of law, etc. Of all country, it is weird that the U.S is turning anti-immigration.
But even never minding that, you could say a lot of things : The U.S.A is a country literally built by immigrants. The native-american are a minority in their own land. So is it surprising that a lot of people in an immigrant country support immigrant ? Then, there is the dirty economic secret that illegal immigration fill the low-wages jobs that citizen don't have to lower themselves too. A lot of ties, rule of law, etc. Of all country, it is weird that the U.S is turning anti-immigration.