I think Twitter is not doing as well as some people think, as you point out, it needs work to be profitable.
I think Elon sees clearly that payment processing systems are very profitable, if you can get people to use them, and placing a payment processing system in a place where people already transact with each other socially, produce content and seek enrichment makes sense.
I think the potential of this model is very great, and the huge response from politicians to squash Mark Zuckerbergs idea of a stablecoin on Facebook points out the vulnerabilities of Traditional FInance to this business model.
I think Elon enjoys shocking and trolling people. But he also knows how to make money, and given his experience with PayPal and his statements about WeChat, the move to make Twitter do more, including in the future payments is clearly on his roadmap.
As for the X rebranding, it's a platform based on attention, and he needed to get more attention on it, plus make people think he is serious about changing the nature of Twitter, and I think changing the name is one step in that direction.
People don't give Elon enough credit for his diverse set of skills, and his record of hard work and determination to solve problems.
While we would all like to see blockchain based systems, Elon isnt done yet, lets give him time.