Malgastar is a powerful verb meaning "to waste" or "to squander". It's cleverly formed by combining mal (badly) and gastar (to spend), and the -los ending on malgastarlos means "them".
In the song, Peso Pluma cheekily outlines his plan for success: "El plan A era generar billetes / El plan B era cómo malgastarlos" (Plan A was to make money / Plan B was how to waste it). This word perfectly captures the track's hedonistic and carefree vibe, giving you a taste of the corrido tumbado lifestyle.
This song is a toast to making it big after a long time of having nothing. Peso Pluma kicks it off by saying he's drinking "Vino tinto pa' curar heridas" [Red wine to heal wounds] but he'll never forget the days "que no había tortilla" [when there were no tortillas]. It's a huge flex about leaving poverty behind for a life of luxury, parties, and getting back at people who doubted him or were ungrateful. He drops lines about how people who left him didn't do so well on their own, reminding them "Se olvidaron muchos que les di la mano" [Many forgot that I gave them a hand].
Beyond the come-up story, the song describes a wild, celebratory lifestyle. The plan is simple: Plan A was to make money, Plan B was to spend it, and Plan C involved "Joyas, putas, y la adrenalina" [Jewels, whores, and adrenaline]. It's blunt and over-the-top. He's listening to techno, feeling the drugs kick in, and name-dropping luxury brands like Coco Chanel and even referencing Pablo Escobar's long hair. The whole vibe is summed up perfectly when he asks, "¿Cuál estrés? Ando relajado" [What stress? I'm relaxed]. It's the sound of someone who has won and is enjoying every single minute of it.