This once high-flying fintech stock has become ridiculously cheap.PayPal (PYPL 2.39%) is down by about 80% from its 2021 highs, and to be fair, there are some good reasons why. At that point, the company's leadership was telling investors that the platform would reach 750 million active users within the next few years (it was around 400 million at the time).Not only did that turn out to be unachievable, but PayPal's active user base completely stagnated -- and continues to slowly decline. In addition, there ...