It looks more like Elon Musk bought Dogecoin long ago, and now decided to raise the price by writing about it on Twitter. In any case, it's good that such famous people are promoting cryptocurrency. Despite his "weird" reputation, many people follow him anyway.
Not just followed, the lucky ones that have investments in Doge Coin over the years had the opportunity to make profits from there investment and I think celebs and moguls like Elon musk will always cause some reaction when they say something about some particular projects.