Roku (NASDAQ: ROKU) minted a lot of millionaires in its first four years as a public company. The streaming device and software maker went public at $14 on Sept. 28, 2017, and it soared 3,325% to its all-time high of $479.50 on July 26, 2021. A $30,000 investment in its IPO would have blossomed to $1.03 million.

Why did Roku's stock crash despite strong earnings? Flimsy reasons behind the price drop could amount to a buying opportunity.

Roku shares dipped sharply after posting Q3 results, owing to a less-than-optimistic adjusted EBITDA outlook for Q4. Read why I remain bullish on ROKU stock.

Today, Roku stock trades at a market cap of $9 billion, which is a five-year forward price-to-earnings ratio (P/E) of 15. While cheap, it is not that much lower than the long-term market average. Unless Roku's stock trades at a premium earnings ratio in five years, the stock won't be much higher in five years based on these estimates.

Roku (NASDAQ: ROKU) and Shopify (NYSE: SHOP) both experienced major growth spurts during the pandemic in 2020 and 2021. More people stayed at home and streamed videos through Roku's devices, while more shoppers made online purchases through Shopify-powered stores.