I can't imagine that a Mexican cartel either needs the money or wants the spotlight shone on them.
My guess is that it was a pair of lone wolves who thought they could get away with something. The fatal flaw in that thinking is that afterward, they can't hide their sudden wealth and spending, and that alone would draw suspicion towards them.
But then, we wouldn't be talking about very smart people.
-PJ
There’s a lot of talk about the dumbery of the kidnappers, but so far, they have evaded capture.