Both maybe, this guy is influential and he showed his interest in crypto, so people seeing that very positive.
It would bring huge money if the guy will put his money in crypto, more money will come due to the ETH's potential and we are in the early stage.
I don't think Elon Musk actually have big interest in crypto, and in Ethereum in particular. This guy seems to be very busy with his ambitious innovative products under developed in both Tesla and SpaceX. He said on media that he continously works intensively to reach his ambitious targets for both companies, and for human society. For him, money is not a matter, innovation is and what is care about. In contrast, I totally agreed that whichever tweet from Vitalik always have big impacts on crypto market and Ethereum.
We never know, every businessman knows the risk of investing, what if he is planning to diversify his investments in crypto.
He would be very welcome as he can influence people to join the space, the minds of the businessman are really unpredictable,
why would he tweet instead if he does not have any interest, this guy is not John McAfee, I think he is serious.