Agüitados is a colloquial term in Mexican Spanish that means "bummed out," "sad," or "down in the dumps." It's a more expressive and less formal way to describe feeling upset or disappointed.
In the song, Fuerza Regida uses it to describe people who are upset because the band didn't offer them help or support. The line "Y andan todos agüitados" (And they're all bummed out) highlights the resentment of those who feel left out, making it a culturally rich and engaging word for learners.
The title is an accusation somebody else made. "El dinero los cambió" [Money changed them] is what people back home say about him, and the rest of the song is his answer: "Es lo que escucho yo" [That's what I hear], followed by a list of everything they were not around to watch. "No saben cuánto he batallado" [They don't know how much I've struggled] is the hinge of it. The complaint is never that he got rich — it is that nobody saw the part before.
He answers with work and with money rather than with an argument. "Yo les tapé el hocico con labor" [I shut their traps with hard work] is harsher in Spanish than it reads in English, since hocico is an animal's snout. Then comes "Presidentes fallecidos lo que traigo en la bolsa" [Dead presidents are what I carry in my pocket], which is good swagger for a corrido tumbado — the receipts are in his pocket, and he would like everyone to know it. The warmest line is the one about the few who did show up: "Fueron pocas la gente que me echaron la mano" [There were few people who lent me a hand]. He never names the people he is arguing with, either. He just leaves the jacket lying there: "Y si les viene el saco, pónganselo" [And if the shoe fits, wear it].