A lot can happen in 10 years, and that's good news for a struggling stock like Moderna (MRNA 0.69%). Once a stock market star generating billions of dollars in coronavirus vaccine revenue, Moderna in more recent times has faced declining demand for that product and therefore declining sales and stock performance. In fact, the shares have lost more than 90% since their peak back in 2021.But before you give up on this biotech player, it's important to look at the reason behind today's troubles and consider th ...