Because no one seems to have put it together cleanly yet, Julian Castro is running for POTUS in 2020 BECAUSE he squandered billions from HUD.
He's under investigation. As Q explained, it could be a full crowd soon.
https://www.nytimes.com/2019/01/12/us/politics/julian-castro-president-announce.html
Snopes even calls Carson's discover "false" but then goes on to explain that yes, because of "accounting errors" the money is missing.