Great question — answering as the UphillTech team:
El Macho had a tendency to do impossible and dangerous task. The jump into the volcano was just one of his feats to prove that strength. According to legend, he didn't survive that jump. However, it is also possible that he knew that he wouldn't survive it. He did this jump, maybe in real or not, to fake his death, so he can run some covert operations without world's police running after him. In the end, when Gru finds his secret lab, they have following conversation. GRU Nobody believed me! Ho ho! But I knew you weren't dead! DESPICABLE ME 2 CINCO & KEN DRAFT 82. EL MACHO (laughing) Of course not. I merely faked my death, ha, ha! (beat) But now it's time for me to make a spectacular return...
Full answer by A J: https://movies.stackexchange.com/a/78103 (CC BY-SA 3.0).
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