If you think $100 isn't enough to buy great growth stocks, think again. A$100 investment in Nvidia 10 years ago is worth more than $25,000 today. It won't be easy to identify the next Nvidia, but that's just an example to illustrate the power of investing. The earlier you start, the more you can give your money the chance to compound over time. If you have$100 to invest every month, you will be well on your way toward creating a powerful retirement portfolio.SoFi Technologies (SOFI -1.24%) and Nu Holdings ...