Will the United States ever have a candidate like Milei, and if so, who could it be?

Rand Paul is one of, if not, the best senator we've ever had. But he's not radical enough. In 2016, his campaign strategy was for solidarity with the party, not for a populist uprising. He knows his stuff, but his strategy as far as I can tell, has always been to play nice within the system. That's not Milei. I personally like Adam Kokesh. He's always been nice to me when we've met, but...I'll just say that he is not likely to be a successful presidential candidate any time soon and really, I don't think he's particularly into it right now. He did run to be the LP presidential candidate in 2016. His campaign goal was to abolish the federal government and take it through a bankruptcy and dissolution process. Honestly, that's not going to be a winning message. The name I have in mind is going to be divisive within the LP, but the closest I can think of is Dave Smith. He has a deep understanding of libertarianism, knows how to convey it, and understands the need for a populist movement to be successful. He maybe doesn't have the flamboyance of Milei and he is not, himself, an economist by trade, but he could just lean on Bob Murphy for it. From your criteria, he's the biggest libertarian celebrity known for being a libertarian (iow, not counting people like Drew Carey, Vince Vaughn, etc), and he is the biggest libertarian influencer today. Also unfortunately, it doesn't look like he's interested in doing it despite seriously flirting with it this year. Honorable mention goes to Spike Cohen and Thomas Massie.