Mark Cuban said he once supported Donald Trump's campaign until he realized that Trump was someone who never learns.Michael Reaves via Getty Images; Joe Raedle via Getty ImagesMark Cuban told the "All-In" podcast hosts that he used to talk to former President Donald Trump a lot.During Trump's 2016 campaign, Cuban said he tried to give some advice, but it went unheeded.Cuban said he would try to engage Trump on policy but it "never got anywhere."Mark Cuban wasn't always a never-Trumper.In an interview on the "All-In" podcast that was published Thursday, Cuban said he was excited to see then-candidate Donald Trump, once an outsider candidate, run for president in 2015.What soured the billionaire on Trump is that, according to Cuban, the former president never listened.Cuban said during the podcast episode that he was once enthusiastic about the prospect of an outsider running for office."Alright, this guy's got no chance to win, but I think it's great because I don't like traditional politicians," Cuban said, recalling the time he saw Trump go down the golden escalators in June 2015.