Musk previously owned an online banking site known as x.com, which would later merge with PayPal, another service founded by Musk, which then became a separate entity with Musk no longer being involved it.
And when Musk was forced to complete the purchase of Twitter, he announced plans to make Twitter into a “Super app” like China’s WeChat application, which can be used for payments.
Musk’s hyperfocus on X might also be because when he was in his twenties, everything “cool” was having an X in it, like XForce and stuff like that.
He also wanted to create his X Corp company to have a single X as its name, but he couldn’t do that because there was an Alphabet company already using that name.