Walls have a long history of keeping out undesirables. Only man made object visible to astronauts in orbit during day light is the wall in China.
Conservatives have long said you will get more of the behavior you reward. Our laws currently reward people who come here illegally. If you really want to curb illegal immigration you will be in favor of changing the laws that incentivize it. If you don’t talk about changing those laws, then you don’t really care about illegal immigration. I’m sorry if people using their brains is offensive to you.
For example, I have a friend who moved to the United States legally with his parents when he was 12 years old from overseas. He later went got an EECS degree from a very good university, then he later got a master’s in computer science from a good university. In short, he will never be on the public dole. It took him 26 years to become a citizen by the time he was 38 years old. During those 26 years many people who came here illegally and didn’t respect our system got their citizenship before him. In fact, he would have been better off coming here illegally he would have gotten citizenship a lot sooner. The fact that people like you want to ignore these problems and just wish them away is one of the reasons we can’t get anything accomplished.