alt Hacker News> Exaggerating a bit, but I'm fairly sure the Spanish speech was: "if you kill the other guys with your much better weapons, you will reach El Dorado"
And they basically did. Not a singular city of gold, perhaps, but the Spanish looted tens of billions of $$ worth silver and gold from Central/South America between 1492 and 1550. Which is all the more impressive given how little European manpower it took and how low their relative incomes would've been at the time.
... where gold is "gold and cochineal". The red dye brought back to Spain was much higher in value than the gold!
Ironically, Europe already had cochineal, but they foraged the source (parasitic beetles), while the bronze-age Aztecs had the brilliant idea to farm them on planted oak forests.