The betting markets suggest he might not be the nominee. The increasing worries about his gaffes that cause his staff to already reduce his appearances this far suggest he might not even be capable of finishing a general election campaign. The donation maps that show Bernie's domination getting most donors with Warren a definitive second suggests Biden might not have the actual support the polls imply. And the fact that Buttigieg has been steadily collecting a huge amount of money from the every wealthy neighborhood suggest the rich Dems are not so enamored with Biden as they were Hilary.
So yeah it does look like you believe the polls are infallible when you ignore every other data point except selective polling. Nothing to suggest" is not really a fair or true statement:
ELIZABETH WARREN OVERTAKES JOE BIDEN AS FAVORITE TO WIN DEMOCRATIC PARTY'S 2020 PRIMARY: U.K. BOOKMAKER
He's been getting hammered for massaging people's shoulders and being on the wrong side of racial issues for months now and is still dominantly in the lead. He also continues to dominate the others among black voters. Until that changes, he's the leader of the pack by a good distance. The gaffe machine stuff is already baked in.