What the assholes are missing is that the drugs are coming in through checkpoints. They aren't being smuggled across the border where "The Wall" could have stopped them.
And the seizure of more drugs could mean that more are being smuggled, or it could mean that interdiction is becoming more effective.
Regardless, the point people are missing is that the drug trade is a "pull", not a "push" economy. People wanting drugs is what makes it lucrative to smuggle them. Cut off the demand or try harm reduction approaches.. because the other problem is "enough fentanyl to wipe out entire cities" would fit in a briefcase. So, uhh... good luck with stopping that.