This popular trading app could be a generational company in the making.Investors are starting to value Robinhood Markets (HOOD 4.65%) like a generational company in the making. The stock has had a great run over the past few years, and while it looks expensive with a market cap of $132 billion, Robinhood is just getting started.The reason why it's not too late to invest is that there is so much opportunity ahead for this company. For example, Cerulli Associates estimates there is$84 trillion of wealth that ...