How can you know that Musk hasn't sold a single Bitcoin? I guess he (personally) can buy or sell crypto currency anytime without anyone learning about it, and he is in the position to manipulate the market is to publish some tweet, and he is not ashamed of doing it. It is a dangerous combination.

His activity makes so little sense (like, first chilling bitcoin through Tesla, making the bitcoin price rise towards the moon, chilling Doge a lot, and then short time later (through Tesla) telling that ... "nah, bitcoin is bad for the environment, we'll skip the idea of taking payment in bitcoin. Perhaps we'll support some other crypto currency in the future that isn't so bad for the environment", followed by a tweet that lifted dogecoin with 16%.

Dogecoin has exactly the same problems as Bitcoin when it comes to the environment. The energy level spent on Doge is, just like with bitcoin, roughly proportional to the value of the coin. Chains like the Hive blockchain does not have that problem as no PoW is done (Well, there is some energy expenditure with Hive too ... but at least not spent racing to find a good hash value).

I'm a big fan of Hanlon's razor - never attribute to malice that which is adequately explained by stupidity. The problem with that is that Musk is not stupid, hence I find it likely that he has a financial motivation for publishing his market manipulating tweets. And even if that's not his motivation for manipulating the market, it would be stupid of him not to buy or sell some before publishing tweets. Musk is not stupid, and Musk is an expert on earning money.