The Latin American fintech company still has plenty of room to grow.Nu Holdings (NU 3.34%) probably hasn't minted any new millionaires since its IPO on Dec. 9, 2021. The Brazilian digital bank went public at $9, but it dropped below $4 a share over the following two years before bouncing back to about $12.But through all of those wild swings, many major investors stayed bullish on Nu's growth potential. Warren Buffett's Berkshire Hathaway, for example, still holds a 2.2% stake in the company. So could Nu ev ...