I really don't get what's so hard for you to understand about this. Cade thought Marty was rich from laundering money for the cartel. From Cade's perspective, there's the cartel money, and there's the money Marty earns from laundering the cartel money. Cade likely believed he was being paid to leave town by Marty cuz he was such a thorn in his business's side. Again, it would not be the first time Marty would have appeased a local threat to prevent them causing trouble with his operation (that's how his daughter got her job). Marty didn't just have the cartel kill Ruth cuz Marty doesn't command the cartel. Also again, Cade was spiraling out of control after killing the federal agent, so his head wasn't completely clear....he just saw his lifeline fall out of the sky, so he took it. Clearly he was wrong and it was the cartel's money that they were just using to lure him into a trap.
Maybe it is just recency bias but I feel these have been some of the best episodes of the entire series. Episode 5 may have been the best of the series. It's really starting to feel Breaking Bad-esque to me now in terms of the show's atmosphere, the foreboding feeling, the cinematography in some spots even... 
why would Marty give cade a dime. Cade can't protect him from the cartel. Any attention Marty gave that nicca was a a favor to Ruth.
