Sen. Rand Paul (R-Ky.) tells me in an interview for Sunday's "Axios on HBO" that cryptocurrency could eventually replace the dollar as "the reserve currency of the world." Why it matters: The senator says he's begun to ask that question as more and more people lose confidence in governments, which used to have a monopoly on money. Context: When Paul ran for president in 2016, he accepted donations in Bitcoin — part of what gave his campaign its youthful appeal.