That is an interesting theory but people have been heading for opportunities in El Norte since at least World War II.
It does bring up another point though. We talk about the cartels as “drug cartels” But that is only one part of their business. Their real business is smuggling routes. They control the route and anything that travels on those routes north or south gets “taxed” Drugs, people, guns, money, avocados, whatever.
When illegal border crossings are up there is plenty of money for everyone because illegal immigrants or just another commodity for the cartels to move. We see criminal groups on this side of the border hitting each others stash houses and kidnapping immigrants to ransom them back to their families. They are literally a commodity to these people.