Over the past few weeks, I’ve had the chance to mentor several early-stage fintech founders—some still at idea stage, some with a rough prototype, all incredibly passionate. These conversations stirred up a lot of memories from my own early days as a founder: the scrappiness, the uncertainty, the optimism (and delusion), and the invisible walls you only discover once you run straight into them. This is not advice from someone claiming to have it all figured out. This is more of a conversation I wish someone had with me years ago—before I burned time, money, and energy learning these the…