Joe Biden, who hasn't even officially said he's running for president, is on the polls now, falling far behind both Hillary Clinton and Bernie Sanders. Why he thinks he can possibly jump in the race now and win makes no sense whatsoever. He will never beat Hillary Clinton and neither will Sanders for that matter, no matter how much I would like him to. Biden doesn't have the right influence, the right resources, the right team behind him.
Hillary is the most resourceful by far, she has a former president at her back, name recognition, money, influence, power. Then Bernie Sanders, "feel the Bern", with his large mass of supporters, massive influence on the internet and his "sincerity" as a candidate. But then there's Biden who doesn't have much to offer the race, no new ideas and nothing exceptionally special about his candidacy, his run for president would just be a failed dream and a waste of money if he were to run. It would further divide the Democratic Party and just hurt those candidates who have a chance.