for example at market close of $45.08, the market is betting there is a $45.08/$54.20 = 83% chance that this transaction goes through.
there are certainly individual stockholders who are buying because they like his involvement, but that is tiny compared to people buying and selling a very near-term bet
This assumes the price without the transactions goes to $0.00!
> The social media company’s shares were little changed at $45.81 in New York on Thursday, a sign there’s skepticism that one of the platform’s most outspoken users will succeed in his takeover attempt. -- Bloomberg
So while the news of a major stakeholder with the power to join the board and affect how things are run did cause a significant blip in Twitter's stock price, the attempt to buy it outright doesn't seem to have affected things much. Even if we (incorrectly) assumed that all of the rise from ~$40 to ~$45 is associated with the possibility of Musk paying $54 a share, that suggests the market assigns only a ~36% chance of the deal going through.