The fact that they are dumping stock just means that they think the company is overvalued, which I think any sane individual that is looking at the market will infer. They want to sell on the upside.

It doesn't mean that it's a scam. The vaccine may work, they may be profitable, and they may have developed tech and processes that can be used to create other mRNA vaccines on a fast timeline even without all the world aligning to help them. It may also be that the amount of growth priced into the current stock price is just unrealistic even if all of this is true.