When I first became interested in the crypto industry (June 2017), it also seemed to me that I had missed the most interesting events and the price of bitcoin would no longer rise. 

So I started looking for an alternative to Bitcoin.  I started looking for the "new undervalued bitcoin".  I have invested in cryptocurrencies such as Dash, Monero, Bitcoin Cash ...

Perhaps Elon Musk has a similar motivation.  He sees Dogecoin as the new popular Bitcoin.  At the same time, Elon Musk is a media personality. 

Therefore, he has the ability to influence the price of the Dogecoin cryptocurrency with his tweets.  He probably likes to do it.