Bitcoin is considered a likely candidate for X Money due to its size, trust, and adoption by Elon Musk's companies like Tesla and SpaceX.
"well the first answer is perhaps the most obvious and that's Bitcoin that's simply because aside from being the biggest and most trusted cryptocurrency out there it's also been adopted by a few of elon's companies already specifically Tesla also earns a stack of 9,720 BTC making it the sixth largest publicly traded company to hold BTC on its balance sheet meanwhile SpaceX which is a private company owns 8,285 BTC"