Nubank just hit a milestone that sounds impossible: it now banks over 60% of the entire adult population of Brazil. It’s not a fintech startup anymore; it’s the bank. With a stunning 80-cent cost-per-customer (vs. $15 for rivals) and 42% profit growth, the stock (NU) is ripping to all-time highs. But here's the catch: it’s all happening just 48 hours before their Q3 earnings report.