He doesn't have a job. What else is he going to do until he gets elected to something?
His only shot at a vice presidential nomination would be if somebody who isn't a White guy is nominated.
Maybe he's actually going to make that happen, taking enough votes away from Biden (and even from Bernie) to throw the presidential nomination to somebody else, but I think he's running because people are telling him to do so.
Not necessarily handlers, though. Nobody goes to a Beto event without being a fan, and the fans tell him to run, and who's Beto to disappoint them?
“He doesn’t have a job. What else is he going to do until he gets elected to something?”
True. Running for office is the only thing people like him know how to do.