The cartels are making billions smuggling humans and drugs into America. Do you really think the cartels are going to cross back over and say "Welp, that's the job. Back home with us!"
Fuck no they won't. And since the US Government refuses to do a damn thing about the border, and has refused to do anything about the border for decades, the cartels operate inside the USA as they will.
It's going to get far worse, until Americans are forced to defend themselves against drug cartels and the blood starts flowing.