Nahh...Its not about having a wall or 500k guards. Its what they will do to you if they catch you, THAT is what makes the difference.
The reason it went WAY down during Trump is because the perception that they would be sent back ASAP (not always correct). Right now they SEEK OUT the authorities so that they can get a processing card and get sent into a city somewhere and begin getting services.
If you made it clear that EVERY SINGLE border crosser (men, women, kids, doesnt matter) who is caught or found would be put in prison for 2 years then promptly shipped back to some other country illegal crossings would drop by a HUGE number. If you then built a decent wall and had a few roving border guards but who were tasked to shoot people who entered illegally (like they do in many countries) then ALMOST NOBODY would try to cross the border any more, only the most desperate drug dealers. Illegals would be near non-existent and street prices for drugs would soar.
So, it is only a matter of WILLPOWER that keeps us having immigration problems. That would probably solve a lot of drug problems as well. Tens of thousands of American lives saved every year.