Investors who have followed Amazon (AMZN -0.43%) for a long time are aware of its path to megacap status. What started as an online bookselling business that pioneered e-commerce has evolved into a tech conglomerate with a $2.2 trillion market cap.While that is a testament to the company's rock-solid business model, it also presents a challenge. Companies that reach such a size tend to grow more slowly, not because of deficiencies in the business model, but instead due to the law of large numbers.Nonetheles ...